I am also a light typist and a Topre fanboy. I currently use a Realforce 87U variable silent, an 87U 55g and an HHKB. The variable is my favorite board in terms of feel. With that said, I think the HHKB is perfect as a 45g uni. I'd leave the HHKB just as it is.
Regarding the lighter Topre switches, heavier typists won't feel the tactility. But as a light typist, I find them quite tactile. The analogy I would offer is to set a grape on the kitchen counter. If you lightly smash it with the palm of your hand, you'll feel the grape give way as it crushes. However, if you slam your hand on it, all you feel is the countertop. With any tactile keyboard switch, the tactile feel is directly related to key strike force. The higher the strike force relative to key resistance, the less perceived tactility.