If you love the JV3-get another one. The print heads are different on the 5. There are a lot of similarities, but they are not the same machine. There have been and continue to be some issues with the 5, but that is normal on a new machine roll out. There were issues the the JV3 series when they first came out.
If it ain't broke-don't fix it!
Why isnt anyone bringing up the JV33... isnt that the JV5, but only with 1 head carriage... and cant they do 1400x1400 as opposed to the 720x720 of the JV3
Personally unless your main goal is production speed I'd go with another JV3 if you can find one.. we purchased a 2nd JV3 last year just before the JV33's came out. we had the option of going with the newer machine but didn't. The reason we did this is because it keeps your overhead down. If you run 2 different printers your keep twice the ink on hand twice the consumables and so on. I run the same profile on both printers and get consistant color.