Best use for four 1.5" insulation slabs

[thehobbster]

So I busted up some cubicle partitions and they had some 2x4 feet sections, and then some odd shaped ones. The odd shaped ones are being used to make twelve 12x16 inch traps like the Ikea ones in the pinned thread. I need advice with the 2x4 footers.

I measured the density and it is a 705 equivalent. They 1.5" thick. I figured it'd be easiest to make a 6" bass trap, since it is 705 and all adds up to 6". But I'd prefer to have two 3" panels to use not only as reflection panels, but to use as a makeshift booth, standing them up around the mic stand.

I've always read that the early reflection panels should be 2" thick and made of 703, because 705 actually doesn't absorb the higher frequencies as well as 703. Is this true, and is this significant enough for me to not use this material to make two reflection panels?