Yup. Bushys, Impluses, Angels, Cyborgs, Egos and Timmys all work on the same principle.
I should have been more specific about the ASA - You can have 2, one on the bottom of your grip which your tank screws into... assuming your using a screw in tank. The other ASA - which BTW is threaded the same as the tank ASA, is what your High Pressure Regulator screws into.
I was reffering the HPR ASA, the Eclipse BM2Ks use non-stadard threads so if you want to get a high performance HPR you'll need to buy a new ASA..... like one of these:
http://www.tantrumpaintball.peachhost.com/ct_PRzenb2kasabl.htm
Regarding the who rail/drop debate find you what ever is more comfortable for you.
IMO people with long arms should use a rail so that they dont have to bend their wrist/elbow much when firing. If you have shorter arms then go for a drop forward. Its all about being able to hold and fire your marker with max comfort.