My first Topre was an all-45 RF 87u; I hated it. It was too light, and I made all sorts of typos due to unintentional input.
I then upgraded to the all-55g 87u and the problems went away. I was much more accurate.
Then I wanted to try the HHKB, so I got a Type-S, which, like all stock HHKB's, is 45g as well.
Except...while the weighting is supposedly identical to my first RF, the HHKB is NOT too light, and I type very well on it. I can't reconcile the difference, other than to wonder if the difference has to do with the fact that the HHKB switches are case-mounted as opposed to plate-mounted.
The side effect of this, though, is that when I switch back to my 55g, I find it to be too heavy now, and get fatigued after a while. This despite being able to type without trouble on supposedly heavier switches like Orange Alps, Buckling Springs, etc.
I've always wanted to try the HiPro model, but I can't help but wonder if it would be too similar to the RF45g, or if it might be closer to the HHKB, where 45g is not a problem.