I don't know if it is taboo or not but I'm going with both the same size.

No idea either, but I used the same size faucets for both my prep and regular sink. Looks fine to me!

I used the same size for both of mine when I had both. My prep sink was about 17 inches, I think.

Good idea thank you. On those faucets, yes. Moen makes TWO versions of these, one for the big box stores i.e. Home Depot and Lowes and a second version for plumbing supply companies and the like. When I reviewed the same faucet at big box stores, not so great. When I reviewed the faucet on several plumbing supply companies, rave reviews. The vast majority of the bigger companies make two entirely different versions of their product line. I am not buying any fixtures at a big box store.

Just be sure you're correct about different versions. Check the model #; if they are exactly the same, then they are the same, regardless of what the people posting reviews think.

Manufacturers cannot use the same # for two different versions. Yes, some do make lower end versions for big-box stores, but not all do -- some actually sell the same in both places. Often the big-box stores can sell exactly the same fixture for a lower price b/c they buy in volume and pay less than the plumbing store.

Thanks B !

I used the same faucet design in two sizes for our kitchen sinks.

Use whatever size works for its intended use. Nobody will be measuring and judging unless it's too damned small to function.