In reply to fire_munki:
I don't think it matters much, I've got a Smart but tend to use a belay master, just because I had a few lying around doing nothing. That does mean I don't see it cross loading at all, whereas a Grigri much more likely to cross load.
One thing I've noticed is that, compared to the SRCs I was used to , it stays in the same place so it's wearing a nice groove in the belay master - something to think about is the cost of the replacement krab.
Sentinels make a nice belay krab but must be slightly less kind to the rope, but I haven't used mine with the Smart.
HMS versions of the Twin Gate and the Magnetron seem a bit OTT for a simple job like belaying.