Is he running the subs under the mains or using the Lokes internal highpass? If he is highpassing at or above 60hz I would pass and save the money.
the Sasha are a lot more dynamic but once highpassed the dynamics of the Sabrina should be greatly increased. Larger speakers are almost always better but subs used correctly make such a difference it might not matter.
the Sabrina’s measurements show cone break up in the mids, or a least a very strong peak at 3k off axis. Oddly people don’t seem to complain about it though.