Unfortunately, the i1Pro Photo 3 Plus I was sent needs to move on, so whilst I've written a lengthy overview of what it does, I've not had a chance to make any detailed analysis of the results.
The review is at
http://www.northlight-images.co.uk/x-rite-i1photo-pro-3-plus-review/I do have some profiles built with the new kit, and have saved measurement data - email me if you'd like a look. Any results/impressions/analysis welcome!
My impression is that if it does something you specifically need (transparency/M3), then it's a good deal, but the older i1Pro 2 still has a place. Definitely an update aimed squarely at the commercial market.
The M3 mode is UV Cut, so there is that to consider in using it.
Just one other thing - if you're using the original i1Pro then get a copy of i1Profiler v1.8.x as well as the new V3, since there are some limitations in license updating. Now, I don't know the details of this, but would note that old kit (the 6+ year old i1Pro) won't be supported for ever.