[cpeterso]

I really like your suggestion to use hours/days/weeks/etc without numbers. A similar suggestion I read for estimating (originally outside the context of software projects) was to use numbers with just one significant digit, so your estimate options would jump from 8, 9, 10, 20, 30, ...

The estimation mention I dislike the most is "t-shirt size". There is no clear relationship between S/M/L/XL. At least story points let compare two tasks. If you try to give t-shirt sizes points (e.g. "M = 2*S"), then you might as well skip the t-shirt abstraction and just use story points.

[novembermike]

The argument I've heard for T-shirt sizes is that if you go to numbers people try to add them together when that's just not how it works. I do agree that T-shirt sizes don't work that well though.

[cpeterso]

I see what you mean about trying to think abstractly instead of about numbers. But once you have t-shirt sizes for some tasks, what do you do with them? You can't compare them. You can't convert them to date forecasts. You can't use them for sprint capacity planning like you can with story points.