Nice to see the article, Pete; so glad you're back in the mix again and able to ride once more. Too close a call for you; way too close!
As for the pots; I understand completely. Anodized aluminum provides only partial protection of the substrate if the roughened pores formed during anodizing aren't closed (sealed). Even then, corrosives can work their way through to the aluminum beneath. Yes, that Lap water was likely very corrosive!
Between titanium and stainless, I almost think I'd choose titanium. In the past, I've found some poorer-quality stainless bottles can develop a metallic "taste" depending on the makeup of the water they carry, apparently due to leaching of nickel. I've found titanium to be "flavor free" in my use, so I think that would tip the scales more toward of the MSRs.
All the best,
Dan.