LPG may be a higher octane, but it's also has a different calorific value and burns slower, so you tend to need to advance the timing by 5deg to get the best performance (not many kits have a timing advance module built in). the BRC kit I had in my 200sx DID have such a module built in, but my BRC qualified installer didn't have a clue how to set it up...
50deg heat increase on a 800deg cylinder is nearly a 10% increase.. I'd say that's worth monitoring and not assuming it would be fine, but then the whole point of having my install was to save money, not to push the boundaries of performance at the risk of an engine problem and I ran a BRC Fast unit without any 'lube' for years without any problems, so I'd agree it's not necessary.
Of course, the small advantage of a vaporiser LPg system is that it's water heated, which when pushed hard actually works as a water cooler as the LPG expands! Don't forget to have a thick a pipe from the tank fitted as possible (else you'll be looking at a 4k rev limit on gas) and for got sake don't let them drill a hole in your bodywork. I have mine installed behind my number plate, which was on hinges - James Bond stylee.
Good luck, but don't get carried away chasing figures on LPG, it's meant to save you money after all, so do realistic savings calculations before going ahead!
Rich