I recently (6 months ago) started using IC in my Federal Paper reloads. I use it with an S4 to make handicap loads that look totally factory. Good stuff. I tried it in some singles loads and liked it too.
I tend to use Clays for singles and Titegroup for handicap in AA and STS hulls. But Int'l Clays is very nice. It really just depends on whether you have wads for a flaky powder like Int'l/Clays/Green Dot/PB or a dense powder like TG/SuperHandicap.
I had somone at Hodgson I shot with one day recommend Inernational, showed me two recipes in their manual that he said are the closest to Rem Nitro's you can load yourself. I use a Downrange wad and load either 1 oz or 7/8 oz at 1,300 fps. I think it's relatively clean burning, but it's all I've ever loaded. It's not very popular, not a lot of places carry it. a big retailer had some sitting on their shelves so long, they gave me a deep discount if I bought all the 8# jugs they had. I must have been the 1st guy in years looking for it.