Before I started to use a straight razor, I would always use just water with a Mach 3. When they started adding those weird gel bands on the Mach 3s for a smoother shave then it was definitely not necessary for me to use anything else.

I've never had an issue with razor burn or anything like that. I've never had soft water softener or anything like that anywhere I've lived either. However, I've never really gotten the smoothness that I'm getting with a straight razor.

I don't know if I can attribute that to only using water (ie. I can't tell if soap / cream is helping with a closer shave) or if my straight razors are just that much better than a Mach 3. I lean towards equipment over water only, though. The Gracie that Max restored and honed for me could probably do better even if I used just water.

It really comes down to time for me. I will put off shaving a couple days just to find the time to do the full lather and straight shave because it's fun. If I really need to get shaved for something immediate I can always fall back to a quick water only shave. I've only had to do that once since starting to use my straights. Most of the time I plan ahead or just wait until I have time to do it the long ritual.