The disadvantage of a high-flow mattenfilter setup is the same as that of simply placing a few powerheads at one end of the tank: the water has to flow to the far end of the tank and then back to the filter end, guaranteeing high turbulence. This is the situation the manifold is designed to avoid.
I had a 55 gallon tank set up with a manifold plus mattenfilter (the mattenfilter replaced the round sponges covering the intakes in a standard river manifold). It worked OK, but I never quite got the flow right. With your pond pump, you could simply add some plumbing so that the outflow is at the far end of the tank. You wouldn't have to dig up all your substrate, just enough to conceal the plumbing. You would essentially have created a reverse manifold (the plumbing is now on the outflow rather than the intake side).
Maybe this will help:
1. Standard river manifold, with powerheads and cylindrical sponge over intakes.
2. Mattenfilter and pump with simple manifold.
3. Mattenfilter without manifold.