With the ability to easily add exactly one metric $4!+-ton of chinesium/brass to the trx4 portals, the high center of gravity can be more than totally offset. Having gear reduction downstream from the diff gears and shafts means that they are under less stress, and therefore, less likely to fail. It also reduces (not totally eliminates) torque twist. The trx4 also starts out with steel links, with the largest rod ends available at this scale (larger than RPM rod ends.) While the motor isn't all the way forward, it's 2/3 of the way there, which gives it a head start in having a forward weight bias.
My cousin-in-law was in this same boat just last month, and after much consideration, we both agreed that the trx4 Sport was the model to get. All business, no b.s. gimmicky parts. Wanting to see how far he could go without putting money into it, we stretched the rear links by putting jato rod ends at one end, ditched the battery tray and receiver box, moved the esc and rx to a piece of lexan attached to the front body mount, made a front battery tray with another piece of lexan and Velcro, flipped the bumper mounts, spaced the sliders up even with the side electronics trays, trimmed the body, took some preload out of the front shocks, and threw on some weighted Redcat Iroks my son had laying around. For $339, he ended up finishing 3rd (of about 20) at his first local competition, 2 weeks after his first time driving a crawler. He has since added 10oz of brass to the front (~$30) and purchased some $15 1500mah 3s batteries that fit perfectly across the front of the frame rails. Promodeler 470 servo and Hobbywing wp1080 ESC are next on the list. He has visions of something halfway between a C2 and 2.2s rig.
I've had quite a few crawlers from many manufacturers, and am far from being a fanboy, and the trx4 sport is the one I'd recommend to someone coming into the hobby. Sure, Wraiths will out crawl it, and my kids E10 and Gen7 have no problem keeping up, but they took a lot of modification to get where they are (and still suffer from ginormous axle housings) the Axials also took A LOT more money to get there. The Ascender has also proven to be rock solid right out of the box, but parts availability locally is non existant (not that it has broken much), and the direct-bolt-on aftermarket has slim pickin's. The SCX10.2 kit does well, but by the time each kit + hop-ups has reached $500, the trx4 gains the performance advantage.
Just my $.02