The correct answer of course, is to get both.
But if that isn't in line with what your budget can afford, I would be leaning more towards getting the one they are offering you outright. I can't say for certain, but I suspect that the auction guns are going to be very expensive as those interested in them are going to base their bids on what similar guns are currently selling for on the open market, plus I see a premium on them for the provenance coming from the CMP.
Right now USGI 1911's are going for big bucks, with even relatively poor condition guns bringing $1500 to $1800 and those in nice condition topping $2500. The earlier the gun the more they seem to bring.
I am fortunate in that I bought several dating from 1914 up through 1944 before the prices climbed into the stratosphere or I would have been trying to get one of the lottery guns.