The HK P2000SK is proven and known. The P224 doesn't have much of a track record (if any). Personally, I do not adopt a new design for at least two years after release. Too many companies are letting their customers do the final QA and this is not acceptable for guns for serious purposes.
Since you already have a P2000 and like it, this should be a very easy decision, and not just because of mag compatability. Identical manual of arms, decocker in the same place, mag release the same. In a moment of stress mixed with terror, you shouldn't have to try and remember which gun you have and how it works.I want the DA/SA trigger systems...and I have the P2000 and like it and shoot it well...now I wanting something a little smaller...I am leaning towards the HK because of what was stated eariler about inter changing the mags...also I the grips on the HKs feel thinner in my hand and seem to fit me better...I do think the Sig has a better DA trigger out of the box