I've been adding icons as I find them/want them, but kind of holding off because I was wary of hitting the limit and then having to delete, so the idea of extra, permanent slots is fantastic, and something I would probably most certainly use.

And as an RP'er who still mostly functions on IJ because of icon slots (it is HARD to get RPers to move over and away from 100 free slots), I love it as an enticement for Rpers. Paying for something and being able to KEEP it from account to account would be lovely.