I set my Masi up with half-step gearing and I like it for some things. In practice it makes fine-tuning the cadence easy. Half the shifts require only the front, and the other half require the front and one click on the rear. If you're used to the front shift being a big overall range shifter, it doesn't work that way. But it encourages me to ride harder because those front shifts for fine-tuning are so easy, and that's a good thing.

A gear calculator shows what works and what doesn't. There really aren't many options. The rear spacings need to be X and the front Y where Y falls in between X, end of story. If you want either X or Y to be smaller jumps, the other must be also.

In my case, since my Masi crank is a 144BCD Campy the small ring had to be 42. The lows I wanted required a 42/34 combination. So with Pastor Bob's help I spaced 6 cogs as evenly as possible between 14 and 34. Given that spacing and small ring, a 1-1/2 step would have meant a large ring of 54 or 55, producing a high gear at 100 inches or more which I really don't need. So 1-1/2 step is out of the question. So 1/2 step is the only viable option. Rings of 46 and 42 would have been a nearly perfect half-step but it brings the high down. A 47 big ring is also good with a better high. A 48 big ring starts to slew the crossover points away from halfway between the rear spacings. So I decided to go with 47 and it has worked out well.

In practice I've also discovered that the 5-tooth front shift is pretty small, pretty subtle. Had I gone with a 46 big ring I probably would have felt that shifting the front didn't do anything.

Maybe you can find a different way to do it. But with the low I wanted I had few options. YMMV.