I really need the white ink so badly, and if this is the case after the release I will not hesitate to buy ucjv300.
I recently visited Mimaki. Saw every machine they make. For what I do, it is not a good fit. The ink is raised on the media, and is thick. If your in the signage/wall/window graphics niche, it would a good choice. Especially with the 5 layer printing and the effects with backlit. Decent scratch resistance, but not as good as HP Latex. The UJV-100-160 prints faster than the the UCJV, but its only capable of 3 layer printing. When you purchase the machine, you have to decide which way you want to print white ink. It can either be setup to print under, or ontop. You cannot have both (UJV). Now with the UCJV, you have the option. But the UCJV is a turtle when it comes to speed. It is actually slower than the UJV. Clear option is not printed during the normal passes. It has to print the whole job, than roll back and lay clear over it. This applies to special effects as well. Rasterlink and setting up the white will probably take a lot of training and learning curve, it all seemed pretty complicated to me (I use flexi). Also, if you do print and cut, you will have to import your cut lines into the RIP with Corel or Ai. it does not have the ability to add reg marks, if your using non Mimaki cutters.
When the new HP is released (hopefully in Feb), it will be a 64" roll to roll with the white option and bulk ink option as well. I'll most likely purchase one for both of those features.