Keep in mind that you can build up any combination you want for less than the price of three cassettes.....Miche has first position cogs up to 15T, and middle/last position up to 29T.

Gear Inches are practically meaningless without knowing what size tires you have.

16T with a 53T ring is the same as 14½T with a 48T ring.

Actually a 13-23 would probably make you very happy at much lower cost than new chain rings.

13-14-15-16-17-19-21-23 - giving you almost the same ratios as a 48T ring with a 12-21.