I have tried the resin-cast options and they are very nice to type on. They keep the shape of the hi-pros exactly since they’re molded from the original caps. I believe that I’ve tried both Blizzard and Idea23 and they were pretty much indistinguishable to me.
If you’re putting hi-pro on an hhkb you’re going to sacrifice something in the way of legends or profile so, as long as you can touch-type, resin-blanks might be one of the “purest” options.