I consider RMC first rate. They are a totally different animal from MagTech
MagTech are thin brass with a large pistol primer pocket and meant for black powder loading ( though there are some who have developed smokeless loads for them). You can resize the primer pocket for 209 primers, but the thickness of the brass base makes this less than ideal. MT because they are thin walled require oversize wads ( 14ga for 16ga MT Shell) and cannot use 16ga wads w/o a over sized nitro card)
RMC are milled from solid bar stock, are 209 primer sized. They have thicker walls and you can use the normal size wad for that gauge. They can easily be used for smokeless loads.
RMC are expensive ($70 per box of 10) but they are extremely durable. I have some thar have taken more than 100 loadings are stiill are good. I have heard from some that they can loaded more than a thousand times, but I have not gotten that far and have stopped keeping track.
One challenge I have discovered is the brass fire forms to the chambers it is regularly fired in and when you move it from one gun to another, if the latter gun has more narrowly cut chambers they need to be resized. Resizing is difficult even in a monster press as the walls are very thick. As a result I reserve a lot of 60 16ga for my Purdey and 70 16 for my Christophe and Greener.
Downsides on MagTech
1. Really meant for black powder,
2. Oversized wads
3. Pistol primers do not work as well with smokeless as 209's do
Only downsides on RMC brass are:
1. Expensive up front
2. Not a huge volume of specific tested data
3. They are tough to resize
