are you looking to compete or just for home use?
If for competing, you have to consider how you would transport either 2 chubby's or 1 party (weight vs their foot print in your vehicle/trailer). Also if competing, you can cook at 2 different temperatures with 2 Chubby's, use different woods in each one, etc.
If you are cooking just at home, do you really want to tend to 2 fires, 2 smokers, etc? Depends on how big of parties you throw, but I would think the Party would be big enough for personal use at home. 12+ slabs of any kind of ribs or 6 briskets, 10 butts, etc is pretty high capacity for home use.
What is nice about the G2's is that full pans fit in there, so you can cook chicken with any other meats, just cook it in pans so no chicken drippings. Is that way you mentioned chicken in one smoker with the pork in another?
Do you have any other smokers? If so, you have capacity there too to cook at home if you need more than the party.