I've heard both bars (not in a direct comparison) and they both sound great. I couldn't honestly say which one sounds much better but either one is probably one of the best soundbars available. IMO I'd be more inclined toward a P1 -- adding HDMI to a soundbar just adds needless complexity and potential headaches. I know at work they were having trouble with lots of handshake issues and dropouts with the P2 as well as the Deftech Solocinema XTR. IMO speaker manufacturers shouldn't really be messing with HDMI considering its inherent complexity. Martinlogan has it right with their Vision - optical only. I don't really think the lack of processing lossless codecs really matter on a soundbar - your soundbar is likely applying so much of its own DSP on top of the original track to simulate surround or whatever that it's an entirely different animal than having, say, an AVR decode a DTS-MA track.
^^^As far as the Harmony, it wil probably work for your Panorama, but I don't think the 300i is a good choice since it lacks the screen. The 300i may control some functionality but if there it a button that the original Panorama has that isn't mapped to any of the harmony's tactile buttons then generally the harmony relies on moving said commands to the screen of the traditional harmony which IMO gives you much more flexibility, so I'm not sure ow/if there's a way around that potential problem on the non-screened models.
ht Panasonic 60" ZT60, Monitor Audio: Silver RX6, RX Centre, Radius 90HD; Martinlogan Dynamo 700, Marantz SR5006, PS3, Oppo BDP-103D
2ch Sony KDL-32W650A, Sony BDP-S1000ES, Marantz PM8004, JVC T-X3 tuner, Monitor Audio Silver RX1, REL T3, Apple TV, Peachtree Audio DAC•iT, Sennheiser HD598
lr Panasonic 50" ST60, Sony BDP-S5100, Apple TV
pc Energy CB-5, Audioengine D1, FiiO A1