Crossing the 4-tuner limit with a single device is an issue regardless of type. You have a bunch of Legacy receivers, so upgrading your outside equipment to DishPro would be very expensive - you'd need either a $200 DPP44 switch, or a bunch of DP Adapters.
However, a DP Twin LNBF driving a DPP44 would give you a lot of flexibility. Note that the Twin connects directly to the DPP44 without any other stuff - that's the advantage of DishPro over Legacy for the outdoor gear.
The DPP44 is the new do-everything switch. It's the only DP thing that can handle your Legacy receivers without the expense of external adapters.
It is also able to drive a dual-tuner box with a single feed when you use a DP Separator (low-cost little box). Finally, it can be cascaded with another DP switch to add more tuners if needed, but the DPP44 can handle up to 4 dual-tuner boxes - and that type is likely what you would be adding - replacing an existing tuner at the same time.
Once you're DishPro, there's LOTS of installation flexibility. Note that you MUST have RG-6 rated at 2150MHz to use it. Coincidentally, the symptoms of bad cable with DP are a loss of even transponders.
It's a tough decision - $85 Legacy Quad vs. big bucks to go DishPro. It all depends on how much money you're willing to spend.
OR if you have must-carry locals on a wing satellite, E* is obligated to come add a second dish - you might have to commit to locals for a year or something. The typical second dish hookup would involve a DP upgrade - it's worth cheking into.