The shop I sort of work at (still, no longer on the schedule but am "on call") runs a Fall CX series (including one of the few North American UCI 1 races) so we see some of the local riders' bikes and some do run sew ups. Some of those riders use sealant in their tires. These tires seem to have less bleed down or "slow leaks" but when punctured by an outside object don't seal as well as a tubeless tire can. We attribute this to the more likely greater casing cord damage (given the higher thread count and lighter construction overall) and thus a bigger hole to plug. A few riders given up running sew ups on their CX bikes what with the cost and efforts that sew ups have compared to wire ons (clinchers).
The local gravel riders seem to run fewer sew ups and more tubeless set ups with sealant. We don't get as much feedback with them as we do from the CX racers. That gravel rides are less about winning they tend to get more riders and more riders who have less bike sense in general. (Bold statement, I'm good with any flames
) Andy