I have a single T-800 filling two 300lb sacs and its not bad if you aren't in a huge hurry. I use a T-800 on each sac to empty and it is plenty fast. I normally fill while getting gear/rope/beer in place and empty while winding down at the end of the day. Works great for me. 3/4" bilge hose, pvc plumbing, and brass parts (not to mention the pumps) are cheaper too.
The stock MLS center sac on my Malibu is filled and emptied with a 700gph. The two 300lb sacs on the T-800 fill in about the same time. When emptying, the separate T-800's are done well before the MLS sac.
So, if the two or three minutes makes a big difference to you and you like searching for oddball plumbing, I recommend the T-1200.