@tthomashardie Nope, I haven't used the Bernzomatic Flame Spreader. Yes, the MAPP gas does burn hotter. That's actually why the Searzall people tell you to not use it - it can burn out the screens of the Searzall. If you watch the setup video on their site, you'll see that the spacing of the flame from a Propane tank is very important - and why their setup instructions are so precise. It's also possible to burn out your screens if you don't do the initial seasoning/burn-in properly.
It's actually a shame we can't buy odourless propane (that smell is actually added to propane and natural gas, so people know when they have a gas leak). If it wasn't for that additive, you wouldn't have any chance to get odd flavours on your food.
That is one of the benefits of using something like the Searzall - keeps your foods from getting the flavour of the gas.
I wasn't sure what flavour MAPP gas would impart to foods, so gave it to a friend of mine to give to his father who does plumbing. :)
I don't use the Searzall for finishing off Creme Brûlée though - you want a finer flame if you're doing the small mason jars in a Sous Vide bath.
As for my Sous Vide experience, nope, I've only been playing with it for a month or two - I just try to do my research before kicking off an experiment to make sure the results are what I should expect. :)
Happy cooking!!! :)