I'm comparing this shock to a 2015 Monarch RL . The RL has a lever which gives you only two options - fully open and locked. The lockout is excellent and really firm when engaged, but a big hit will still open the shock up.
Compared to the RL, the RCT3 locked position is not as firm and doesn't give you that "hardtail" feel when sprinting out of the saddle. In this respect, the RL's lockout position is excellent, whereas that on the RCT3 seems to be just a firmer version of the "pedal" setting. If you want a proper lockout, go with the RL.
Pedal mode seems to do what it supposed to. Shock doesn't feel particularly firm, but there is a noticeable slow speed platform operating. Breakaway force on this shock tune seems really soft, so works quite well on an Anthem where a lot of platform is not required because of the Maestro suspension design.
The open mode feels fairly plush but surprisingly not as plush as the open position on the Monarch RL. Perhaps with some more riding in its plushness will improve. I haven't had this shock apart so at this stage I don't know what the valving looks like and whether there is still some sort of platform (or preload) operating on the shim stack in open mode.