I would dig them up in managable sections with as much soil as i could around them and move them to their new or temporary home. if done well, I think that they'd be ok. You do have to expect that there may be some casualties.

Irises are pretty tough. They may not all bloom this year, but I imagine they will survive. It sounds like they should be divided anyway.
Renee

I agree with Renee, sounds like they need division anyway. You are going to have so many iris to replant, if you lose any you'll never notice. Iris are very tough & can easily handle division now, you'll just lose bloom.

Thanks for the advice. We did move them this weekend. Divided the 2 areas into manageable chunks to move (about 15 or so) and ended up with 6 nice plantings. Tried to keep them in the soil they were already in and planted them like that. So far so good.

Thanks again!