I have both. I have cooked with the DX2 many times and it is awesome. One of the best investments I have made for long cooks.
I recently purchased the Party for use when I don't have electricity or need to run another smoker (without the added cost of another DX2). That and I was curious to see how it worked. I have only used it a couple of times but it worked like a champ.
I don't think you can go wrong with either one but I like to plug in the DX2 and not have to worry about batteries.
LBGE, 22.5 WSM, Backwoods Chubby, 26.75 OTG, Weber Performer, Ultra fast Packer green Thermapen, American flag Thermapen