In reply to Matt CS:
I did it, as I didn't climb much outdoors (still don't do as much as I'd like!) and I wanted to be able to take my cadet group climbing. (I then moved away from my cadets for just over a year in between training and getting around to doing my assessment, but never mind...)
As a course, it was good, informative and enjoyable, theres more climb coaching content than the SPA had, and for that reason I think a lot of SPA holders then did a CWA training course as it plugs a gap (now the coaching scheme is out, I think this is unnecessary) The assessment was good, I was given 4 CWA trained students for my group work, which was interesting (the other two people on my assessment had 3 novice-ish climbers)
I would like to follow up with my SPA at some point, but not in the immediate future.
I'd say if you wanted to primarily teach indoors, its better than SPA, but if you are aiming for outdoors soon, go the SPA route.