Thanks for the thought and time you have all put into helping me think this through. For the record, here are a few more details I probably should have put into my original post.

The boat is a Pacific Seacraft 40 with 100 gallons of water tankage, exactly the same as the Crealock 37 I cruised on single handed for years. The watermaker is a pur 80.

When in the Bahamas I would average 1.6 gallons of water per day. (I did say I was frugal about it.) That would give me about 2 months between fill ups. Now there will be two of us and probably much less frugality. I'm guessing we will still get about 3 weeks out of our 100 gallons.

I always filled the tanks in Spanish Wells at 10 cents per gallon. That's probably gone up, I think I saw 15 cents mentioned recently. But as many of you wisely pointed out, it's not about cost but freedom.

Thanks again for your help. I'm back to being undecided.