Spoke to a bunch of companies reps, which is where the parallel circ idea evolved from.
My 1.25" supply from the boiler gets split into two 1" pipes to the parallel circulators, then they recombine into a 1.25" pipe to the house. This was done to get a higher flow capacity because the next size circulator would have been overkill, and over 3 times the cost.
My circs have the flow checks, but I would prefer to use a regular one, so my thought was instead of recombining in a tee, and then go through a flow check, that I could skip the tee and use the flow check to bring the circulators piping back together. I have everything just figured it could cut down on a little piping and fittings. If it's a bad idea I won't do it.
Also, how close or far away from the boiler should the low water cutoff be placed, same goes for the supply temp sensor well?