I have a similar setup of what you're considering with a P2000 (the P2000 was the precursor to the P30), and a P229ST (stainless steel frame).i can get a p30 for about 1016 with no night sights with a frame that wont rust . or i can get a sig p229 nitron finish with night sights for 832.
i hear you have to grease the daylights out of the sig to make sure it functions properly and that just a few drops will take care of the hk. so if someone could tell me that has dealt with either of these guns the truth about these issues that would be great. i also heard that the sigs will get surface rust fairly easy. i just hate to spend 184 more dollars and then still have to buy night sights to go on the hk which will be another hundred bucks. advice needed. thank you all
Your P229 under consideration has an aluminum alloy frame and stainless steel slide, so those components should not have rust issues. Sig rails need more lubrication than the HK.