No regrets at all, love the 20's. The improvement in grip for the summer tires over the all seasons is very noticeable in moderate temps, and per the earlier comment on this thread, even at 30-40F the summer tires on the i3 still grip just fine. I understand where that mindset comes from, though, as I've had some summer tires that gripped as well as hard plastic in sub-freezing temps.
All of the i3 wheels are forged, so I think the instances where you would sustain wheel damage on the 20s and not the 19s are very limited. The i3 tires/wheels (in any size) are a bit more at risk from potholes vs more common wider setups, just because they're more prone to fit more easily into a hole than to run over the top of it.