Good decision on the Roland, you won't be disappointed!
In my opinion it could be hard to upsell the metallic printed products for the price they would need to be (more expensive inks, lamination needed on ALL products, much longer printing time). The customer simply either expects to get the metallic for (almost) the same price as standard colors or then go with standard colors only. I also thought about the advantage over competitors with the metallic inks with my last purchase, and it is cool the first prints you see with it, but be realistic and calculate how much metallic/white you can actually sell. Have you had ANY real inquiries about the special colors the last year? How much more money do they want to spend to get those colors? Do you currently have a good subcontractor that has white and/or metallic capabilities or could you find one?
Could it be better to gain speed on you machine and sub out those one-two jobs per year that could need white/metallic and not having to deal with the hassle and expense of special colors instead?
It's your decision, but once again I'd strongly recommend you to consider if you really need the special colors.
The VS is a good machine so you won't be disappointed in that aspect. Good luck!