I was in the same position as you, bought one just over a month ago and absolutely loving it. Wish i had actually bought one earlier, thing is even if it's new it's got a chance of going bust anyway from all the problems i hear. But i have friends with both replaced and non replaced consoles who love it to bits either way.
I took the plunge and think it's worth it, overall we can't make that decision for you, you have to make it yourself. It sounds like your thinking like i originally was and that was your not sure about a 360 and maybe not buying it due to that. I mean it's like your wanting one but looking for a reason not to buy it, ie. using them breaking as one.
If your not fair enough, as all people who buy stuff which have a supposedly high break rate are bound to be a bit concerned about shelling out. But although there is a lot of breakages, there are also a lot that haven't been replaced and are still going strong. It just seems to be luck of the draw and newer consoles doing it a bit less than the older ones.