Inspired by this thread I bought a battery powered air blower! I chose the Dewalt DCV100 because it fit the battery system I had already.
I had been debating whether to buy a regular electric pump for inflatables for a while. But they seem cheaply made, noisy, slow or terribly expensive. They are single-use and I wouldn't take it in the boat anyway, so there would always be a need for a good manual pump. The handheld multi-purpose air blower seems like a more appealing option to me, and today it arrived!
After a quick test I can conclude that it takes less than 30 seconds to fill up one side chamber (out of three total) on my Zodiac mk2c from totally empty to full. Then it takes another 30 - 60 seconds using the trusty old foot pump to get it to pressure.
Needless to say, inflating or deflating the SIB is now a quick job! But it wasn't painfully slow to begin with either.