I would like to see 25 or so of the top group shooters shoot a 100-yard UBR agg; I'd be surprised if there were not several perfect scores. (I'm not suggesting that group is harder than the UBR target; I'm just saying that those 25 or so shooters are Top Guns.)
This would most certainly be fun, but we all know it won't happen. Some things, to consider. IBS/NBRSA 25X targets aren't all that common. I haven't done research recently, but IIRC there have been many years when not a single perfect target was shot. Many of the folks who shoot IBS/NBRSA score also shoot group matches as well, the good ones in both disciplines win.
The UBR target is slightly more difficult than the IBS/NBRSA target due to the bullet diameter/dot/10 ring size ratio. In five years of competition there has only been one perfect score shot and the competitors are no slouches. Two of the best (Danny Hensley and Mike Niblett) won the 100/200 IBS Nationals and the 200/300 IBS Nationals this season.
It would take very good conditions as well as some luck and based on past performance and there might be one perfect score, but multiples would be highly unlikely regardless of the field. It is fun to speculate though.
Rick