I have a RM packer and did a review. Kind of a moot point right now as I really can't wear any packer or prosthetic (though I have a nice prosthetic). Anyway, you could probably search susan's and find my review. I think the RM basic packer is pretty nice. It to me is pretty realistic, though I think the balls are too long really, but that's the design so that packer sits inside the balls, which means it won't stick out. Its softer than a Sailor esp the sailor has the core, which I really like about the sailor actually. (Not sure the silicone in RM, I'm not sure what grade. It has a little smell, nothing overpowering, but more so than a prosthetic I have. There are 2-3 layers, so maybe one of them is not medical grade.
The thing that bothers me about RM is the weight, at nearly a pound. I used basically a sock to pack with. I think the weight is such that the best harness would be a jock strap. That would hold it nicely, I think. I think it is worth the price, but if you put in a regular harness I think you might decapitate it. I'm not saying guys don't do it, but it looks like it could be a problem. Mine shows wear right along the shaft where it connects to the balls. But it still is nicely made. BTW, I had a python (or another made by the same folks like viper?) anyway, I think they are just cheap, and not 100% silicone. I don't know maybe silicone foam or something. I gave mine away and never wore it. I really wouldn't recommend the company.
(BTW, I had communication with RM, I thought they were pretty good, mine took a LONG time to get to me due to the fact that I got mine from the first batch I think. I think that RM is a class act company.)
--Jay