There are two T34 variants, one has opening hatches, the other doesn't.
I am doing a build on one if you want to see what you get:
http://www.rctankwarfare.com/Forums/index.php/topic,3200.0.html
The standard electronics are ridiculously complex, and very toy like. You can rip everything out, simplify it and run it on an RX14 for about £15. I have gone the Elmod route as I had a spare main board, and can swap the sound module between my Tiger and the T34, so I only needed to buy an extra battle system.
You cannot change the muzzle flash as it is glued into the barrel. It will not come out.
The weak point is the plastic gearbox, and if this goes awol you can either but all metal gears to replace the existing ones, or fit HL gearboxes though this requires a bit of engineering.
They run on 9.6v using 280 motors as standard, and are very light, so strain on the gearbox is light too. Fitting metal tracks will as always, place extra strain on the transmisson, but it has to be said that the WSN plastic tracks are very high quality.
All in all they are nicely detailed, and everyone who has one says that they make great RC tanks. There are plenty of threads on them and the mods that people have done, Google is your friend.
Rob G