Well, it depends on the cost realy...
If/When your new product comes out it will be significantly cheaper than (in my case) two-three additional rev burners + two-three cheap tachos, then I would prefere to wait.
But since the "new product" is so far away, I have no hopes of getting a price range on it, and with that in mind, I would by two-three more revburners to run two-three more gauges, (fuel lvl, water temp and/or oil press.) if you are able to make a revburner "display anything".
Is there a limit to how many revburners you could have in one setup?
Maybe a new version of SimDash could just list Revburner No 1, Revburner No. 2 etc. etc. on the instruments tab, and then you get a pulldown box to select what you want that revburner to show. (Speed, RPM, fuel, oil press, turbo press etc etc.)