The RG 2027 is FAR superior to the S 7420!
2027=Double Edge trem (peizo), 3 peice tung oiled neck, made in the Japanese factory by the top Ibanez luthiers.
7420=TRS trem, Korean made.
Let's not even talk about the 7420 anymore, it's such a step down from even an RG 7620.
I'm pretty sure the USRG's have alder bodies. The 2027 has a mahogany body. I'm not sure how much difference there will be sonically between these two, but the biggest difference will definatly be the 7th string and the peizo pickups in the trem. You also might want to look at a Universe or an RG 7620.
Just stay away from anything made in Korea with a TRS trem.