The bluegrass lite ones do look light. I got a d30 b&s the other week, it’s fairly bulky compared with nowt but it’s nowhere near as big as I feared. It’s not going under an XC or road Jersey though!
Fit is a bit short (everyone’s seem to be on their charts) and pretty snug. I’m 6’4, 80kg and went for the XL, think I could have gotten away with a Xxl if it existed for a better ballance of length and figure hugging.
The main reason I went with the bluegrass was they were small for the length mind. Most manufacturers only did a long ish one in what would have been too loose a fit.
@weeksy ordered a couple of other ones to check at a similar time so may have a useful opinion on those.