I don’t have an answer but I am playing in the same pond.
I bought an HP LP2475w as a second monitor (two monitor computer setup) which is a Wide Gamut monitor which also has HDMI in. I calibrate it with Spyder Elite 3. I’ve noticed that the Datacolor calibration software has a Rec709 target option. I also have a Matrox MXO2-LE with HDMI out feeding HDMI of the HP monitor. I haven’t tested its new and improved monitor calibration feature yet though.
I will note that the wide gamut is certainly evident when compared to my 23″ Cinema Display. Part of the confusing nomenclature is that Wide Gamut monitors are often described using terms like 102% of NTSC (and “standard” gamut 70something%) without much explanation of the term.
I don’t have answers for you yet but I’d thought I’d let you know that I’m looking at the same puzzle. Of course this isnt’ directly related to the XDCAM EX though. Perhaps there if there were a generic Color Grading forum or maybe a forum for those too cheap to buy a broadcast monitor, we could post this puzzle there.