One of my favorite brands of loudspeaker, pity they are no longer distributed in the UK.
When i bought my current Mission 782 floorstanders i was actually out in search of a pair of System Audio (probably SA1500..) , but the dealer had sold their last pair a few months previous and i just had to buy something :Not Sure:.
Talk about long throw woofers, when my SA1111 stand mounts where on full song i actually could feel the air being pumped from the front reflex port on my face over 8 feet away ! It aided placement
The Nordost cable guy used to use a pair for his demo's at the Scottish Hi-Fi shows.
As you already know, and especially when it comes to loudspeakers, the only way to find out what they will sound like in your listening room is via a home demo....
For me my Missions only have small drivers anyway and so it probably wouldn't make much difference.
The SA1111 stand mounts that i once owned had more than enough bass response for me. I bought them after hearing them at a HI-Fi show back in about 1997, they were the best in show for me despite their small size and the company they were in.
They were on the end of some very serious source & amplification though and alas i was never able to afford to re-create that sound in my own home, so although they sounded pretty good i never got them to sing as well as knew they could. At the Hi-Fi show i had to physically check that there wasn't a small subwoofer connected up too, the dealer had set them up so well.......