Butler - it's nice to see a no-vent jacket occasionally in this thread. I only have one no-vent suit (a midnight-navy worsted flannel MTM job with peak lapels and so it therefore has a vaguely tux-esque vibe when worn at night, so the lack of vents seemed appropriate), but that suit's getting a little old now and I'm idly thinking about ordering a new but similar one next autumn... bespoke this time, but once again with no vents. We'll see... they are tough to get right, it seems to me.
There's very little room for error. I have a dinner suit without vents that fit perfectly until I gained about 4-5lbs over the holidays. The ventlessness makes it that you have to stay in a very narrow weight range, at least that's my limited experience.
Sounds like useful motivation.
I ordered my current one when I was a little heavier; not by much, but enough that the suit is slightly big on me, so that's part of the reason I'm thinking about replacing it with a bespoke one. Shame, really, it was actually one of my favourite suits for a long time.