I switched out JV33 over to Triangle JVV cartridges about a year ago. Not a single problem at all. Prints beautifully and I believe it has a slightly wider gamut. I did not flush it at all - I did however time it to where I was as low on the oem inks as possible, then when I was between jobs where one of my oem colors was going to run out - I switched all cartridges over all at once. Did 3 ink fill ups to make sure it was fully on the triangle ink and was off to the races.
One thing I did do and I strongly suggest - this will depend on your RIP as well regarding what you will need to do it - is to create new custom profiles. We run Flexi Pro which has profiling built into the Production Manager and it natively supports an Eye One Pro. Also - another tip - JSI Sign carries Triangle inks - the price you see on the main pages is not the same price once you add it to your cart which is even less.
I have also read many many good reviews about Solaris ink as well but they seem to be reluctant to show ink for JV33 in cartridges but I have been told by them that they do indeed have it and you just need to request it from your dealer. I may go back to a bulk system one day - used to use a bulk system on our old JV3 - which will give additional savings but I have to admit - just plugging cartridges is about as simple as it gets and the JV33 has the ability to autoswitch when one gets low anyways.