RE: Just back after long break and need some help...
I'm surprised this thread has gone without a reply, its can be a very opinionated topic to say the least. Im not surprised at the lhs steering you towards a traxxas product though, its what they stock the most in parts and makes them the most $. It does seem shops are moving away from HPI stuff though, the Baja being an exception. My breakdown is this, run on 6s Lipo, the drive lines of the Savage, Emaxx and Erevo will all fail at some point.
The Savage flux has better diffs, metal trans gears and metal driveshafts, but despite the name they are not "Bulletproof" diffs. Disassembly and re-shimming the diffs will make them pretty darn close though. The flux can also eat transmission gears despite being metal. The rest of the truck, in stock form is stronger than a Emaxx, about even with an Erevo. Handling is a toss up between the Flux and Emaxx, Erevo is better than both of them. Lots of aftermarket parts out there to make a Flux stronger, prettier, etc.
Erevo: The diffs are smaller and not as strong as a Flux. But i wouldnt say weak, again disassembly and re-shimming goes a long way to making them live, especially if you plan on 6s. The plastic driveshafts aren't bad, but they wear out faster than metal. Running on 6s makes it happen faster. The rest of the truck is pretty tough, the transmission is bulletproof. Again, lots of parts to make them stronger, prettier, faster, etc.
Emaxx: I have a soft spot for Maxx trucks, but I can't help but try to steer people away from them sometimes. The diffs and driveline are the same story as the Erevo. But the chassis and suspension in stock form can be on the weak side depending on how hard you use the truck. Unless its just grass and flat surface running, there's what I call "necessary aluminum" for these trucks. Bulkheads are where the a-arms attach and they should be aluminum, I like aluminum shock towers and skid plates also. The other necessary upgrade is RPM arms, at least in the front. Then you'll have a truck that can take a beating and not break stuff in minor mishaps. Knowing these things, I'd still get another Emaxx before a Flux, I just don't like the TVP's, the motor mounting and some other things.
MT4 G3: Never had one, have heard nothing but great things though. No support at the LHS is a pain, but they mostly carry stock parts for the other trucks anyway, the usual exception being RPM parts. If you don't like online ordering, any lhs can get Thunder Tiger parts and if they're a decent shop they order every week so wait time shouldn't be too bad either.
If it were me, I'd have a tough choice between the Erevo and the MT4 G3. I never liked the TVP design and feel it makes things a pain, Emaxx I've had and spent too much $ on them. Erevo I liked alot, but not crazy about 2 batteries, I like one brick a little better. Handling would be similar with an edge to the MT4, but Erevo is more of a Monster Truck without giving up too much handling compared to a Truggy.