I have the RG400 and several RG200 and I love them! The fact that they take protank coils is a plus, since my Davide also uses them. If you don't already have one, get a needle bottle to fill them, it's easier. The RG400's fill holes are a little larger, but the 200's are tiny. I have yet to have one leak or flood or gurgle and use them constantly.
Thank you. I have needles, bottles, a little bit of everything stashed away. I try to buy the biggest tanks I can find. The large capacity of the RG400 was the selling point and the fact that I already have replacement coils that will work.