I just bought one to get my fermentation chamber back. It is still the overflow freezer when the pig is butchered and all the birds are butchered.
Faced with your delema. I would go towards the economics of a chest freezer they are very green.
I agree with you on chest freezers being a more efficient option.
We had to go with an upright for 2 reasons. 1) my wife is too short to reach the bottom of a chest freezer without falling in (we used to have one and it was entertaining, to say the least) and 2) the hole we cut in the basement wall for the addition we built made a chest freezer out of the question space-wise.
Luckily we got everything refrozen and are back in business with both a freezer and a keg fridge.
Euge, you would be amazed at how fast an upright freezer can thaw with the door cracked open. All the cold air just runs out the bottom of the door and that sucks warm air in the top.