OP: You didn't mention if you already had a Topre board, and just wanted one with the high caps too.
If all you want is a Topre board, I highly recommend the Type Heaven.
Here's a new one for just $132 shipped. It's a real, full-size Topre---and while some peeps here have
cited the differences between it and Realforces that cost nearly twice as much, I have one of each, and love them equally well. (Did I mention that the TH is, like, half as much?)
If you have a Topre and are now after the big caps, you'll like them if you you like older vintage keebs like Model M's, with similar high caps. Otherwise, from what I've read here,
it's very subjective whether the Hi-Pro is worth so much extra dough. Personally, I wouldn't expect to type faster or more comfortably on spherical keys than on the modern cylindrical type. I'm perceiving that it's mostly a nostalgia/novelty thing.
Of course the best way would be for you to try one first. If I were in your place, I'd order one from someone who'd let you return it if you didn't like it. Then the most you'd be out would be shipping and perhaps a small restocking fee.