Maybe because REL--like SF--is also distributed in the US by Sumiko, and until SF came up with their own sub it was the package that the distributor--Sumiko--supplied to the reviewer. Also, since REL has a full line of subs, it was relatively easy to match a sub to a given speaker line (such as a T8 to the Toy series). With that in mind, the better question might be, "Why, with REL as a sister company, did Sonus Faber take on the development and marketing costs to come up with their own Cremona M subwoofer?
12-08-11: Erictye
... I am sure SF subwoofer is exceptional. Why is it that over half the reviews out there mate the SF with a Rel sub?
Raul: For all your words you haven't told me a thing I don't already know. However, I can't buy your dismissal of a general speaker maker as having a disadvantage in subwoofer design given that any company can hire just about any designer it wants. John Curl designs electronics for Parasound. Nelson Pass has done it for Adcom. D'Agostino desgined for Aragon. Hsu designed (or consulted) on the Outlaw subwoofer designs. I have no doubt that Sonus Faber hired all the specialized help it needed to come up with a subwoofer to meet their high standards of musical coherency and seamless integration--the areas most elusive in matching subs to mains.
As for Velodyne, its accelerometer/feedback design and low advertised THD is essentially an electro-mechanical version of the negative feedback loops used in amplifier design. Feedback loops were used to excess in the "THD wars" of the late '70s receivers, and only resulted in lower numbers--not better sound--to sell more receivers.
I'm not saying Velodyne's accelerometer is an ineffective gimmick, just that it doesn't prove that it's superior to JL, REL--or Sonus Faber.