I decided to give myself one last ride before deciding on getting the 12-23.

I did a 40mi hilly ride home from work just to see how things went on the 21t and 24t cog on my 12-27 set up. Fact is, I like doing hills, but like the fact I can fall back onthe 24t cog at the end of a grueling ride---the 16t cog is not worth it.

So, again, I may get the Ultegra 12-25---or---sigh---maybe consider getting the Tiagra 13-25 which has the 16t cog. Any issues with this fitting on my Ultegra setup with SRAM chain?

Sorry for being fickle and annoying for overthinking this...