Unbiased opinions?
Mag, I'm 5'3", 110-120lbs? and love my KDX. I came off a YZ80 so had to adjust to the seat height, but after a few rides, wouldn't go back (we kept the bike for about 4 months for me to be certain).
The bike is very friendly to a beginner, but can go when need be (my husband rides it too sometimes). I'm not fast by any stretch, but gaining confidence all the time. You can lower the suspension if needbe, but I think the older model (89-94) is lower to start with than the current one - Brenda/Adam/anyone can you confirm?.
The bike can be modified easily (reeds, pipe, airbox lid etc) and well worth doing. I ride mainly sandy forests (New England terrain is similar). Yeah, I still fall occasionally, but it's mainly in dumb places that I've stopped & can't reach the ground (my guess would be someone about 7' could touch the ground there, so it's just stupidness on my part).
The weight factor got me to start with as I found the bike too heavy to pick up often, so per C-Dave's advise, started running half a tank of gas, which helped (and I was able to) but now find it not a problem. The stock pipe/muffler weighs a short tonne, so ditch that as soon as possible, but then again, the FMF & PC pipes are great to open the bike up anyway, so it's a win-win situation.
Hope that helps some, and as with Adam, feel free to ask any more specific questions.
Oops, forgot to mention: LoriKTM was riding her KDX for 5 years before upgrading to the KTM200, but she had her suspension done before ever riding the bike, so you could contact her too. (hope that's okay Lori ;))
Michelle