A ups is super inefficient, it transforms from DC battery to ac power and then the the pumps power supply has to turn it back into DC. There's losses at every step of that.
The backup systems are DC batteries directly powering DC pumps. The ecotech one for example is literally just a dc battery with a fancy looking cover around it, there's nothing else inside.
Some UPS units also have DC outputs. Take a look at any of the mini-UPS units designed to supply backup power to networking equipment like routers, switches, modems, etc.... A lot of networking equipment is powered by DC, so UPS units designed to power them also have DC outputs rated for 5/9/12/24/48v too.
For instance, you can get a mini-UPS that puts out 12v/2A DC and has a built in 10Ah battery for $45. (single 12v DC output) You could put two of them together for $90 and have 20 Ah capacity.
These mini-UPS typically have (4) lithium cells in them. Like (4) @ 2200mah or (4) @ 2500 mAh cells.
The $45 one I was looking at has (4) 2500 mAh cells, so 10,000 mAh = 10Ah. Put two of them together and you'd have 20Ah capacity for $90. The Ecotech says it's capacity is 18Ah, so I'm guessing it has (8) @ 2250 mAh cells inside. (??)
The only difference I saw was that the Ecotech unit is rated for 12v/
2.5A where the mini-UPS I was looking at was rated 12v/
2A. Depending on what pump(s) you were running, and needing 12v/24v, this might make a difference...
Saying all that.... I run a simple setup with no DC pumps. So any regular UPS would work for my setup.