i’ll give ya a little, unprofessional opinion. i live in texas also, north of dallas, just got a 29er back in oct-ish. been a long time road guy so this was a big, different step, both the off road thing and a 29er. mtbr.com has a lot of great info on mt biking. i love my 29er. i’ve borrowed full suspension 26’s but prefer my 29er. i got a redline mono9, which i didn’t figure it out till after i’d bought it, but it’s a 1x9. duuuh. it had a rigid fork and i got a nice rockshox for the front. at times i kinda wish i still had the rigid fork, i’m still getting used to the movement of the fork on steep descents, freaks me out a bit, but does help with the ride.
another thing that i’m still getting used to is riding over stuff, rocks, roots, logs, etc. you don’t do that on a road bike as you well know, with the 29 inch wheel it’s fricking amazing what i can go over with ease. i have no regrets to my 29er. i looked at full sus 29er’s but didn’t go that way for 2 reasons; 1)$$$, i didn’t want to drop that kinda of cash for a bike i wasn’t sure i was going to ride enough to justify, 2) i’ve heard, i have no idea cuz i’ve never ridden one, that full sus 29er’s are a bit squishy feeling. i didn’t realize it but i had more than 1 salesperson say getting the geometry right on a 29 in frame is quite a chore. i don’t know what the details are but that’s what i was told.
i don’t think 3 rings up front are really needed, i like your idea of a 2x9. mine has guides for cables if i want to put on another ring and dérailleur, but not to often do i wish i had a second ring. one thing that i’ve noticed, and i don’t know if this is a 29 v. 26 thing or changes in my riding, it seems i can stand up and pedal more on a 29er where i think on a 26 i’d break lose on the rear tire. the significance being i don’t need a granny to climb some things, i can stand and power up it rather than stay seated.
it’s just my .02 and it’s prob not even worth that, but i hope it helps. best of luck in your search, the more i ride off road the more i frickin’ love it. after riding a couple hrs i’m trashed, it’s a great workout, both aerobic and anaerobic. one more thing, don’t brake hard on the front in soft soil, esp whilest turning. trust me.