Can you pick his brain...saying you're interested in buying one? I'd ask him
which one he has at work, features he likes or doesn't, which one would he want for a home kitchen.
I make a number of compromises in a home kitchen, but if I had my choice, I'd want what I have at work. For example: I'd want a the exact Cuisinart we had at work. I have a small one and it's very annoying. It doesn't have the volume I'm used to and it overflows all the time. Grr...My housemate has the big Cuisinart...but hers locks in the back, not the front. Again, very annoying.
I would imagine there are features on the Vitamix that are the same for him.
PS. What an incredibly generous gift!