Google them and you'll find quite a few reliability and customer support issues. Also, Highland Outdoors were thinking about selling them -they even appeared in the trade price list- a couple of years ago, but they didn't go ahead: I think, because they (Excel) couldn't guarantee supply. Sorry this is all second hand, but AFAIK no Excel Arms rifles have made it to the UK.
For what its worth, I have tried several different makes/models of bull-pup self-loading rifles in .22RF and have noticed that without exception they have very long and insensitive trigger pulls. I have never owned one so don't know if the pulls can be improved upon. I think the last one I handled was a Walther but not entirely sure.
So much for my supposition that "none have made it to the UK". Simply out of interest I'd want to go down there and try the thing out, even though I suspect it will be pants, if only because the owner must have gone to some trouble to bring it in and might otherwise be expected to want to hang on to it.
FWIW the route I took with a .22WMR was to start with a Remy 597, replace the factory hammer with a Volquartsen one, have the 20" factory barrel cut back to 14" and threaded (IME the stubby little bullets don't retain their accuracy beyond 200 yards or so, so losing 100 fps is less important than the extra stiffness imparted by a shorter barrel), and put the barrelled action into an Archangel conversion stock. It's a kind of DIY VTR carbine, but cosmetics matter less than the fact that it's very accurate (grouping 3-shots into well under 1" at 100 yds), handy when shooting from the 4X4, and its length-of-pull is instantly adjustable for use with rear-mounted NV (something that's hard to do with a bullpup).