Anyone running a Sumiko S-10 subwoofer for music? Impressions? How about Hsu ULS-15?


I have considered both these subs. On paper, the Hsu ULS-15 is the clear winner. But the Sumiko integrates perfectly, according to one reviewer (S-9)
I now have a Rel Storm 3 in my system which I have enjoyed for many yrs now. I have a rather large space to cover due to an open floor plan with 15x20 LR w vaulted ceiling opening to 12 x12 DR with std 8' ceilings. I love the way the Rel integrates in my system and don't want to give that up. This has me looking at others in the Rel line. However, Sumiko, (which was the Rel distributor for years) also makes subwoofers with similar specs and size. This causes me to believe that they have much in common with the Rel and at a better price. The Sumiko S-10 has 12" woofer (down firing) with 12" passive radiator (side firing) & 500 watt class D amp. All the other Sumiko S series are similar to the T series Rel. However the S-10 has similar components and specs as the Rel S-5 SHO which gets very good reviews. So I am considering jumping on the S-10. But I cannot find any reviews on the S-10.  Thus my post 
Anyone with experience with the S-10? I have seen many Hsu ULS-15 reviews, mostly from Home Theater users which leaves me questioning its musical integration ability. This leaves me leaning towards the Sumiko S-10. Thoughts?
BTW, main speakers are Silverline Sonatas (Avalon style)
128x128artemus_5
my good friend recently got the s-10 to use with his magnepan 3.7s and i was genuinely impressed--the sumiko was very fast and integrated pretty seamlessly; seemed like good value. i haven't heard the hsu.
@loomisjohnson 

Thank you. One question if you please. How big is your friends room? Is he using one or 2 subs? Thanks again for your help

arte
his room was fairly large--i'd guesstimate 15 x 18 with fairly high ceilings. he has only one sub and his is a music only system (not movies)