I recently had a 'full' demo of the printer at ND Graphics in Toronto with a rep from Mimaki and a local gent.
I went into it wanting this machine to make up for some of the deficiencies in the L25500 but came away generally unimpressed with the Mimaki.
PROS
-output was indeed beautiful...machine was running slow and at 1440 or something similar, but very nice on some adhesive vinyl
-machine runs about 15 Celsius cooler which should help with some of the media issues, but in the testing they had done, they still needed to get temps up to 70C or more so I don't know if this will fix all the temperature grievances we've all had
-this thing is as quiet as an aqueous printer, very quiet
CONS
-machine costs about $35K plus more for the white ink option
-if you choose the white ink option you will have a slow machine
-both the Mimaki rep and the local rep were discouraging people from choosing the white ink option
-Mimaki rep admitted they were still getting their ink 'right' even up to the launch date
-rep claimed 'huge' cost savings in ink, printheads (they are 'permanent' in the Mimaki), and electricity to justify the higher up front cost, but his numbers were based on a lot of messed up assumptions
-the guy couldn't stop slamming the HP machines which got tiresome after a while
I came away from it feeling like they were still figuring this thing out and I wasn't interested in being part of their real world beta (remember that HP had latex ink in use for a number of years in their larger machines before coming out with the DesignJet). Like I said, I do applaud Mimaki for getting into the market, but for our company, we're not ready to be a testing ground...I feel like we've been that for the L25500 ...we need machines now that can run and run until we break them and need new ones.
One last thing. I'm not sure where they came up with their pricing, but they are totally out to lunch on that IMHO.
That's my take. Go check one out if you get a chance. Pretty cool to see something other than HP in this space but I wouldn't touch it as a production machine.