I've not needed studs for any of my builds or those I've been involved with. Fel-Pro brand bolts are a lot cheaper and I believe work better, for most people.
We put nearly 300,000 miles on our 6.5TD Power Project - the majority of those miles involved towing. The truck also saw many runs on the dyno and spent quite a bit of time as a platform for testing various performance products (i.e. intercooler, water injection, exhaust systems, etc). They were not easy miles. There were no problems with head gaskets.