I think secular Israelis think that Orthodox conversion is like getting a Jewish marriage license for secular Jewish Israeli's. If you can prove that both spouses are Jewish, then you just have to play along and say whatever the rabbis want to hear, even suffer indignities like women being asked to show their underwear (to prove that they are not getting married when the woman during a woman's period or 8 days after) and listen to someone tell you about going to mikveh every month ---I'm not making this up, we know secular Israelis who went through this. Then you have to let a "black hat" rabbi do a religious wedding ceremony (which most of your secular friends and relatives will ignore). But after all that, you have a legal Jewish marriage and the rabbis stay out of your life again.
Secular Israelis do not realize that for conversion, the OJ converts will be asked to agree to live by very strict religious rules for the rest of their lives and lie with the fear of having their conversions revoked for not living observantly enough. The difference is that the Rabbinate in Israel feels that even secular Jews should marry according to religious law, whereas they see no reason that anyone must convert. These rabbis also seem to think that converts can't really become proper Jews and expect them to backslide or revert.
Ironically, most secular Israelis have accepted the idea that only Orthodox Jews are real religious Jews. The non-Orthodox movements are slowly growing in Israel as Israelis discover that it is possible to have a religious component in ones life without it being quite the all-consuming aspect it is for a very observant Orthodox Jew.
If you think you want to do an Orthodox conversion be sure that you are comfortable with a totally Orthodox lifestyle AND the people in whatever congregation you would join. Same could be said about any kind of conversion, but more so for OJ since the religious community can be expected to play a bigger role in your everyday life. It can be a very nice thing to be a part of the kind of close-knit community common in Orthodoxy. But will you be comfortable with people who might be appalled by your religious views? And do you think that you can suppress those non-Orthodox views enough for acceptance by an OJ beit din?
I am lucky to have two minyanim that have many of the characteristics that make OJ appealing while being more welcoming to people who are different (race, sexual orientation, Jewish status, etc) and to more liberal religious view points. And yet our services are nearly identical to OJ services. Sometimes the prayer leader chooses to add the matriarchs, but other than than that there are only a few words that are different all of the Shabbat morning services. And as in O shuls, the congregation knows the service so there are a chorus of voices, not like a "performance" by only the clergy as in some non-O shuls. Most members observe kashrut and Shabbat and people often invite each other over to share Shabbat meals. The community comes to the aid of any family that has needs due to births, illness, or deaths. But an important difference, which I see as a benefit, is that we are completely egalitarian so women lead prayer, read Torah/Haftarah, take aliyot, etc.
Daniel, perhaps there might be a small minyan that is part of a larger Masorti synagogue that would have some of the things you like about O services? One of my two minyanim is a "library minyan"---term used in the US for small lay-led prayer group that is part of a larger synagogue.
I don't know if it is wise to put much weight on future possibilities when deciding on which movement. You could get an Orthodox conversion that is later not recognized by the Israeli rabbinate for religious identity (different from Law of the Return), since these things seem to be changing all the time lately And unless you are actually planning to make aliyah, I don't think you should end up living a different kind of life in Spain that you don't really like just because of that possibility.
As for other Jews recognizing your Jewish status: does it really matter what some ultra-Orthodox lay person that you will never meet would think of your conversion? I would also like to add that I have Modern Orthodox friends who treat me and my children as Jews even if they would require conversion of my kids to marry theirs (or prohibit that in the case of the sons of a Cohen). I think that it is like hechshers (rabbinical supervision stamps on food): we have friends who are fine with drinking lemonade with a "triangle K" hechsher at our house (because it is certainly "kosher") even though they would not serve it in their own home because they or others in their community are think the supervisors may use leniencies they are not comfortable with. Similarly, I think maybe they think that I either am or could be Jewish, they are just not sure about the certification process (whether the rabbis were qualified witnesses by being religiously observant by OJ standards, for example).
Daniel, the fact that you are male makes it EASIER as far as future children. If you marry a woman who has a clear Jewish matrilineal line, then your children will be Jewish by Orthodox standards regardless of you conversion status or even if you are not Jewish at all. I guess you could worry that you would be more likely to meet and marry a non-O convert if you join a non-O synagogue, but do you really want let that kind of prejudice against female converts influence the type of conversion and life you choose for yourself?
So I urge you to decide based on which group feels right. It is your life to live, not that of others who might judge your Jewish status.
Usaurio,
If the trend continues, Judaism will fracture into two non-intermarrying groups, with the fundamentalist Jews becoming a racial ethnic group---non-O Jews will continue to accept converts. I do not believe that non-O Jews are going to disappear any time soon (despite the YU rabbi saying "kaddish" for CJ and basically calling RJ non-jews already). In some ways the split has already happened.
