I think you're better off with the HK in both cases.
The P30 vs 226SCT:
P30 is going to win out on ergonomics, reliability, durability, plus it's made in Germany. The SCT isn't really better than a regular 226 because while the sights are cool the 4 20 round extended mags you are paying for are now made by checkmate instead of MecGar, and they are pretty crummy. You then end up needing to replace them and you can't get the regular flush fit 18 round MecGars because of the extended magwell. Also, the trigger on the Sig may be a little better, but it's still not the SRT trigger you'd get with the TacOps, Elite, or E2 models (none of which I'd recommend either).
The HK45c vs. 220 carry I can't speak to because I haven't shot a 220 carry but I think most of the same rules apply.
I think the older Sigs especially the 228 and 226 are some of the best pistols out there but their current QC isn't up to par, and HK is top notch.
You may hear comments about HK's customer service but most HK owners have had great experiences with CS in the past couple years and most likely you will never call them.