Gray Wolf, what are you're thoughts on using a pressure cooker. I've used one with some success for some topicals that I use on my arthritic bother.
Mixed. Sushicat used them effectively for making large Canola oil extractions at around 180F, while keeping the smell down. We do a similar thing in closed jars, which limits that advantage.
As far as speeding up extraction, temperature and relative pressure are part of the formula for dissolution speed, so increasing either, would reduce extraction time, but decarboxylation and conversion of THC to CBN starts at a relatively low temperature, so the effects will be more sedative; probably a non issue for a topical.
What I've found most effective preserving the THC, is just being hot enough (160/180F), and keeping the boundary layers removed by regular stirring with a low shear wooden spoon. That keeps fresh solvent in contact with concentrated resin, as opposed to a highly enriched solvent in contact with a partially depleted concentrate.