I periodically do a beer can chicken on the grill. Got a nifty twin bird stand, but have only two birds at once a couple of times.
I typically have to rummage for a can, or just put some beer in an empty coke can from one of my taps. While I have heard that it makes the chicken more moist inside, by the time I am done cooking (about an hour), almost all of the beer is still in the can.
What I think does make this an epicurian delight is the prep and method, not the beer. I typically will oil the bird, crush some sea salt, and sage, or do a french herb blend and carefully rub it in, under and all around the bird. The stand makes for a perfect tool to hold the bird in a good postion, and with a little aluminum foil dircectly under the ass of the bird, I avoid scorching the skin.
Honestly, without a spit, I doubt I would have ever ventured to try to roast a whole chicken in my little grill. But in the end, you couldn't tell me if I used a Scotch or a Pale Ale with the bird. Maybe an ounce is gone, and likely some of that ounce is lost jostling to impale the bird onto the stand and then taking it off the grill and off the stand.