Of course it depends on your speed, but I would say its closer to +1/2 hour for Lake Placid. My husband is pretty consistant and has done both races 5 times each. His finishes are from 9:30 to 10 hours in LP and 9:09 to 9:30 in IMFL.
Dan Bryant just did 10:01 today and did 10:01 last year at CDA (Good to see a local kick ass!). I know he is stonger on the bike this year, so like you said who knows. Sounds like support crew has some good data. Might also depend on the day and your training. Flats are hard for a lot of people for so long.
Simple - take the square root of Pi and divide it by the number of atoms in the universe…and 12 to that and convert to hours. That is how many hours more that you will take at IMLP than at FLorida.