Perfect Path DPL approved productshttp://www.dpllabs.com/page/dpl-member-perfect-path
Monoprice or any other company is not conservative with their ratings, they either pass high speed spec or they don't! Some standard speed cables will work with 3D for a couple of reasons.
1. There is a LITTLE fudge factor built into the spec.
2. 1080P, 8 bit at 48 frames per second (24 per eye) which is Blu-ray 3D uses less than half the bandwidth that HDMI high speed is rated.
If you plan on using an HTPC and using 1080P/ 8 bit at 120 frames per second, deep color, 4k x 2k resolution or just want that capability in case you upgrade to something that requires greater bandwidth than go with a solution that you know can handle that bandwidth.
A nice thing about using a balun is you will probably only have to change the balun and not the wire if some new format comes out. There are already 10+ versions of HDMI. However, the best thing you can do to future proof is run conduit in case you have to change a wire.
If you only plan on using Blu-ray and broadcast 3D you can get away with a standard longer cable. I'd suggest looking at the companies that have passed DPL testing and see if they have a longer version of the same series that is standard speed. It is the least risky solution which might work since DPLs testing is tougher than HDMI spec.
Hope this helps.