Hi Juxx I have the small HD with loupe. I've not used other monitors but judging from specifications it does seem a little dated in terms of the features. No scopes, native resolution 800x480, focus assist (rather than peaking).
At the time when I bought it my thinking was to shoot a short movie and I was looking into having a rig with cage and follow focus along with rods, so the loupe seemed to fit in with that theme. The dp4 with loupe mounted is quite big... Later I discovered that this style of filmmaking was not for me, I wanted something more agile, lightweight, run and gun style. I found that the monitor itself can still fit the bill, being relatively small in size at 4.3". It is a bit more real estate than the LCD screen that is built in to your average camera so I find that it does help with framing, and focus assist is good enough.