V970 is not Dual Sim Full Active. The U960 is, and it works without problems (you can call your self on the other sim :-)
The U960 supports WCDMA on SIM2 and TD-SCDMA on SIM1.
I know that because I owned a U960 and have a V970 now (here in my hand).
No MT6577 chipset phones are DSFA, it is simply not supported by the MT6577 chipset. However both sims are online at the same time and can receive calls, also while using internet. Only when one sim is active in a call, the other one will be offline.