the Scoprega pump seems to be perfectly sufficient for inflating a few kites every day. If you are inflating over 10 kites/day a compressor would be nice though
Again, if we're going to get pedantic, the Scoprega pump IS
an air compressor (even if we're not going to get pedantic).
OK, I am not an expert on the subject, and perhaps there are many types of "compressors" but for the purpose of my comments I would define a compressor (for this discussion) as a device that has a high pressure pump (usually piston) and storage tank that would allow for access to large volumes of air at the desired psi quickly.
I think that the vapor condenses into water in the storage tank and that's why sometimes you see some moisture exiting the nozzle when you use this type of system - unless it has a dryer/moisture trap. There are compressors without storage tanks but they might be a bit slow at inflation if they are only piston driven.
When considering the choice between a "compressor" (or scuba tanks) and the Scoprega pump portability, weight, and simplicity were the major factors. The Scoprega is small enough and light enough that I don't mind carrying it a few hundred yards to my set-up spot...and it recharges fairly quickly before the next session just by driving a few miles in the van.
The Scoprega has a 2-stage pump - a fan for inflation of a few psi and then automatically switches to pump for higher psi. And again, for the purpose of inflating kites I think this is a pretty good solution if you want to avoid the back strain. Other than inflating other things like small rafts, small inflatable boats, inflatable racing marks...not sure if the Scoprega has many other useful purposes.
(ps: I do not sell Scoprega products. At first I was disappointed with the problems with the fan material failures, but the company has stepped up and corrected the product and now I'm happy with it. I think the original objective of this thread was to get info/feedback on various systems as an option to a hand pump and what people's experience was