Bought both a 38 and a 40 of the same suitsupply suit on ebay for stupid cheap because I was between sizes in some measurements and figured I'd just solve the problem when I got both of them and donate the one that doesn't work. Now I've got both of them and the 38 seems almost cartoonishly small, in a way that I think is doing really weird stuff to the vents and arms, but I don't actually trust my eye because I almost never wear tailoring.
I guess my question for the folks more well-versed in tailoring is just: is there any point at all in trying to get the 38 let out in the waist to get that flare under control, or am I better off just sticking to the 40? (and I suppose a follow-up question is, if so, what work does the 40 need beyond maybe taking it in the tiniest bit in the waist?)