I have a Merc II on one motorized dish, and a VisionSat iv200 driving the other. They are both outstanding boxes. I prefer the Mercury powerscan, it is configurable, and you can watch the new transponders being discovered in real time. I like the Visionsat picture better, it is configurable ( contrast , brightness, etc) . My pref is the Merc, because I blindscan so much.
I have both a Merc II and Visionsat IV-200, and agree 100% with that assessment. The Merc II has good blind scan (it could be faster, but in my experience it's thorough and consistent.) User interface is simple, and if you want to manually create memories with PIDs from Lyngsat, you can with the "Add Channel" menu. And it's one of the cheaper boxes out there.
Visionsat of course adds PVR functionality. It has an outstanding feature for motorized USALS systems where you can "fine trim" west or east to peak a transponder, and then save the new position. (I do this with the Merc II by using USALS, switching to 1.2, STOP, trim, save position, until I finally got my pointing just right.)
After upgrading the Visionsat to 1.45 firmware, I prefer the signal level meter to the Merc IIs. Perhaps Fortec will change their averaging interval / algorithm and improve their signal meter function in a future release so it too will be more suited for use in dish pointing.
I agree they're both great boxes and outstanding values. For me, I'm glad I started with the Merc II because it seems easier to use to me. But Visionsat's pretty good too, and if you really want PVR it's your choice.
Appearance: The Fortec looks kind of cheap plastic silvery to me, but the box is *very* reliable - more reliable than my Comcast PVR, that's for sure.
Visionsat seems to very occasionally be a little glitchy, but I can't put my finger on specifics. In ever case, a power cycle cures all. To my eyes the Visionsat looks good in an A/V system. Now, if only these PVR manufacturers would put the USB connection in the BACK...