Guncrafters Industries 50GI .... never have handled a Coonan, sorry.
... I have both their 1911A1 and their Glock conversion in 50GI...love em.
http://www.guncrafterindustries.com
I have a 21SF and really feel it’s more than adequate, both on my hip at work and on the nightstand but I’ll admit I’ve been intrigued with that conversion kit ever since they were introduced.