Hey Buckwild,
First post here, but this seemed like a good place to start.
I've got a KX 100 myself. I started on a TTR 125L, got bored with it after about 3 months and got the KX. I'm 5'3" and weigh about 110. I'm a pretty aggressive trail rider and adapted to the KX very easily. It's a fun bike to ride, and mine is stock other than the FMF pipe/silencer, heavy duty clutch (which you would likely need), 428 O-ring chain (a must have), and pro taper bars.
I've been on the KX for a little over 2 years now, and to be honest, it's way too small and I'm a tiny bit smaller than you. The seat height is the main problem, or more the seat to peg height. I've found that particularly when I'm on a steep uphill section, I need to be sitting on the seat almost sitting on the gas tank. Well, that doesn't happen. I start out with my weight on the pegs, but my knees are so bent (think sportbike position) that my feet bounce off the pegs. The frame is so small, it's hard to stay in a proper riding position because I'm so cramped. This can be helped with tall seat foam, though.
But, the handlebars are too low, and tall seat foam would make it worse. I'm working on a set of custom bar risers right now, that hopefully will help, but I'm not so sure. I'm using high bend bars, but I still can't get in just the right position.
Also, the bike is unstable at higher speeds because of the small wheels and short wheelbase. It's very easy to lose the front on it. Ride an XR 50 at top speed for the same effect. You'll see what I mean.
Next, ground clearance. It's not great. Makes it difficult on log crossings, ruts, mud holes, whaever gnarly terrain you choose.
The bike makes great power up top, but I have to clutch it a LOT to get up the steep stuff (WV mountains), and I'm going through clutch plates more than I would like to. They're easy to replace, but it's just one more thing to do.
I'm moving on to a KTM 200 EXC very soon. You may want to check that out. The seat height is only about 2 inches higher and only weighs about 40 pounds more, I believe. Around the ballpark of the weight of your TTR. You can shave a lot of foam out of the seat to get it lower if you need to. And, you're not a new rider anymore, so getting both feet flat on the ground shouldn't be as much of a concern anymore.
I don't want to steer you away from the KX as it is a great bike, but be warned that I'm a little shorter than you are, and it's way too small for me. It felt fine for a few rides while I was adapting to the 2 stroke power, but once I got used to it, I think it's held me back more than put me ahead.
Just a few things for you to think about to make bike shopping more confusing for you! I know how frustrating it is to find just the right bike, and I've had 2 wrong ones so far. Hopefully the KTM 200 will be keeper.
Sorry to be so wordy, just thought you may benefit from my experiences in the field, and I've got lots more I can add.
Good luck!
Amanda