John;
I believe the jacketed data is safe from a pressure point of view, but may lead excessively. My understanding is that one can use jacketed data for lead safely, but not vice versa. If you use hot data with a lot of pressure and heat be sure to check your barrel for leading, that can build pressure very quickly with bad results. However, if the gun doesn't lead excessively then you will have a slightly faster bullet at slightly lower pressure when comparing lead to jacketed.