As a data point, I made an Iddee-style vac with a slider (dump) tray. If the vacuum control is attended to, the only bees that die are the ones the got soaked in honey during a cutout. I don't have any large losses with either of my vacs, but I won't say a single bee has NEVER perished in them.
The big thing is to have the suction just right. I use the large corrugated vacuum hose with a concentrator nozzle and occasionally have to shake the tube to loosen accumulated bees if there's a low point in the tube.
Bees, brews and fun
in Lyons, CO