I was tempted by the Fdeck but wound up going with the OmniCabSim by DSM. The OCS is a different tool than the FDeck HPF -- it's designed to be a cab sim. I have to mention it because it worked perfectly with the Berg CN210 cabs I owned for awhile that were a bit too hi-fi for my taste: I used the OCS to tame the highs and lows (it has both HPF and LPF), and add just a smidge of mid punch.
If you're looking for nothing but HPF, then the Fdeck (or other) would be a better choice, but the OCS has some great features.
If you're looking for nothing but HPF, then the Fdeck (or other) would be a better choice, but the OCS has some great features.