My friend's size 50 Kilo was 20lbs when I built it, from what I remember. I'm sure it's lighter than a Big Shot. Also, if you don't like the fork, it will cost you more money to switch it out. You can't just "service" a fork, unless you're talking about painting it or cutting the steerer shorter (i.e. slam the stem). The Kilo is worth it; you should only consider the Big Shot if you must absolutely have a certain look right away - it being on sale helps a lot, too. As for your size, if you're around a 30 inch inseam, you should fit on a 50. Use a fit calculator if you want to be absolutely sure.