Trax 2.4 TQ no problem, as long as it can control the truck that's good enough. Of course you have $$$ you can go for NPK(S) or other topgear with tons of adjustable function that you basically will not use it. But the battery/charger in Trax kit is basically useless (especially the charger), Trax factory should take this two item out and deduct HK$110 !!
Buy ultimate la, the opptional parts worth much more than the price difference, only the extra central differential worth more than HK$200! Also, aluminium suspension la, anti-roll bar la, etc...etc...
Simple is the best, if you run on-road ( football court, street etc..) and slightly rough track, Slash is better. But if you go on mud, sand, rocky track etc.. 4x4 la !