I have both, I find the SIG fits my hand a little better and feels a little better in the hand. I prefer the HK for ergonomics and primarily the amibidextrous mag release which I find far faster than the SIG.
I find the HK is a little easier to shoot and recoil is a little less than the SIG as well. Accuracy is the same for both my pistols.
On take down - I agree with Maurice above, yes there is the extra step of pushing out the slide release lever but otherwise take down is the same, I have never had a problem taking the HK down.
On price, the pistols will likley be close. HK mags are generally a fair bit cheaper than SIG, MecGar produces OEM SIG mags that work great, better than the SIG mags in my opinion. I dont know of anyone off hand that produces OEM HK mags.
Re warranty - cant help you there, I can say I have better than 6,000 rounds through my HK with no problems or stoppages. No probelm with the SIG either but not nearly as many rounds.
I have a SIG refurb and mine was new in the box, apparently it sat in some deparment armory and had never been fired. The refurbs are good, most departments that issued them likely only had annual qualifications so they were not run hard.
At the end of the day handle and shoot both to see which one feels better to you and you shoot better with. Both are great pistols with great features, it comes down to personal preference.
) and the quality is awsome... the gun is almost as nice as my Beretta 
