I tried the different brands and sizes of caps when I had my cap and ball revolvers and learned the following. I have owned San Marcos Arms, Euroarms, Pietta and Uberti brands. The CCI #10s were too small, the CCI #11s were on the stiff side. I like the RWS #11s, slightly more stiff on fit compared to the Remington #11's but close. Overall the Remington #11s were the best. When I mention "stiff", that is in how they go on and stay on the gun's nipples. A really stiff cap will tend to fall off easily when the gun is recoiling, a softer cap will mold itself better and stay on.
I had a tin of CCI #10s that I tried to sell at our periodic gun club flee markets, no one would buy them. Rather than throw them away I took a small scissors and cut a split into the side of each cap, this allowed it to spread out to fit onto the nipple of my revolvers, worked well and I got my money's worth.
At his time I only have my Lyman single shot percussion plains pistol. I have been using Remington #11s and will order some RWS #11s when I get new supplies this Winter. Might try a tin of CCIs too as the single shot guns are forgiving. The nipple that came with the Lyman was a soft metal stainless steel that had to be replaced after 4 visits to the range. Dixie Gun Works sent me some nice bronze made ones that are much better after I talked to them on a replacement.
In all the years of shooting my cap and ball revolvers, I never replaced the nipples with an aftermarket type, I always used the factory ones. I have read of people putting better nipples on but I never went that way.
AtlLaw...when you mentioned the lack of customer service communications with Tru-Ivory, it reminded me of some of the gun shops in my town. There are 2 of them that I have purchased guns and ammo from, and when I asked them to call me when they got soft tip rifle ammo in stock, or a type of rifle, of which I wanted to buy, they never called me. They asked for my name and phone number, never heard a thing. I won't do business with them again.