Will the BE300 boards fit into the Prisma fan/heatsink body?
Yes! That would be great since there are probably tons of prisma heatsinks and fans laying around with the buy-back. Since you would only need to ship the new boards, you can save money with shipping.
From earlier statements it appears that the power density of BE300 miners will be lower, and so won't need nearly the same levels of cooling. Sure if a few of the screw holes match up you could put them onto Prisma heatsinks but at this point it may just be overkill.
What do you think about the smaller packaged die size and less over all components on the boards due to PMS chip, combined with the lower heat density.. potential for x48 to turn into x96 maybe?
7.2gh x 96 = 2.8TH icy cold Prisma's at ~850w?
I think with the current problems with getting things stable, that the most sensible solution would be a smaller board. If it dies but you've got 15 others in a miner, the consumer is going to mind a hell of a lot less than if you had 4 and 1 was bad. Think Avalon1, mini modules within modules.