If you do go for the DC EWP, consider using the 80. A forum member (Keiren) reckoned the EWP115 he used his on his new 2.5 litre tuned 912 engine, combined with an upgraded alloy radiator, resulted in thermal shock to the block/ liners. The ewp115 flowing a sudden large shot of cold water from the rad. That said, the devil is in the detail regarding programming used to control flow.
And in any case, I found the ewp80 run either with, or without, a controller (analogue), is well up to the job on the 912 SE. And it pulls only 7amps max rather than 10A, which means the sTD alternator easily copes with the load. Plus I've run the ewp80 with an upgraded alloy rad and the STD brass/copper cored rad with no ill effects. The later digital controller programming is superior to my analogue version so pretty sure you won't have issues with the ewp80.
Anyhow you have more experience than most so I expect you'll know how to set it up right regardless of EWP size