4 years of pretty serious battling at Danville, and no issues with the hull.
Never heard of any either.
I am a huge fan of the Pershing, especially as a battler.
In fact, I just replaced the original tracks because they were pretty much worn flat.

If you are considering any upgrades, I highly recommend the gearbox plate made by Daryl Turner and sold by ETO.
http://www.etoarmour.com/products.php?ViewCategory=14
Without it, you have to disassemble much of the inside to remove them, plus it adds some rigidity.

Upgrading to sealed bearings for road wheels and suspension is worthwhile also, and easy to do on this tank.
Several online dealers sell complete sets. like mitosal
http://www.mitosal.com/Bearings.html

480 motors are a good move as well, and with the stock pinion, you are right within the scale speed range.

With assembly, you just have to be really neat with fitting the electronics and wiring into the hull, as it is very tight inside.