I own two Issac Hollis SXSs. One hamer gun and one boxlock. Both are very nicely made. I would put them against the W C Scotts for close comparison. The name recognition isn't ther for the Hollis. Hollis and WC Scott both took in guns from other makers to finish and put their name on them.
I have seen Isaac Hollis shotguns, double rifles, revolvers, etc.
Mine are from the 1890s and then from 1924. I shoot them both.