hey ngtgb:
i have a similar issue as you, but imo you should not be worried.
since, as you said, the front is not thin out yet and you are a slow thinner, then it will take many more years before it will appear to be thinning, in which case you can go for a second HT
most likely however, is that if you take finateride, you will keep what you have at the front.
BTW, don't worry about its side effects, and don't read to much about that because it can create a self-fulfilling prophecy. Personally, i started Propecia about 1 month ago, and so far no sides effect at all. I read somewhere that if you are going to experience sides, it will be within the first 2 weeks. Actually i think sex is even better now. Another thing to keep in mind is that most people bitch when they have a problem while they tend to stay quiet if there is no problem, thus i think the vast majority of fin users have no problem but they don't shout about it in this forum.