I have a 140 gallon tank upstairs and a basement fish room right below. My sump is roughly 100 gallons in size. So yeah, I have a pretty similar setup!

My return manifold distributes the return flow through 4 x 1" outlets.
I have experience with both options you're looking at.
1) Seq Barracuda - when I first set up my tank I was using a Sequence 1000 5000SEQ22 (5000 GPH, so similar to the Barracuda). With the pump running full open through the 4 returns there was WAY too much turbulence and the water was close to splashing over the side of the tank. Microbubbles from the skimmer were also sucked right up into the display despite the baffles in the sump (it's a 6' long sump too so the water had a long way to go).
2) PCX-70 (similar to Blueline 70). This is what I'm running right now. This is a LOT more reasonable. I do have the pump valved back a bit though. It's still quite a bit of flow though. If I had to do it again I'd probably use a PCX-40 as my sump return. The PCX-70 sucks 280w of power (measured with Kill-A-Watt type device), while a PCX-40 uses only 90-100w.
The SEQ1000 5000SEQ22 is on my closed loop now.. All in all I've got over 6000 GPH of circulation...
I'd suggest using the Barracuda for a closed loop, even if it's over the back of the tank. These sequence pumps are amazing flow pumps and you'll get so much more value for each watt you're putting into them if you use them in a closed loop setup.
Hope that helps!
Tyler