So I just went thru the gear ratios for my cassette comparing a 28T vs 30T vs 32T (current).

One click down (smaller cassette cog) on a 28T ~= 32T gear ratio. It's not always exact but its pretty close. See the color coded chart. Plus I gain a whole new gear = 28-51.

Where I ride, I'm mostly in 51, and then in 45, 39 and occasionally 33, maybe 28. When I'm descending its mostly maneuvering and brake checking here and there. I'm never in the 10, 12, 14, 16. And I never ride this bike around town.

So I'm leaning toward a 28T Oval.

I'll grab some quick links as well. If I don't use it, its nice to carry in the hip pack in case there's a mishap.