I would like to hear your success progresses with your vents and tinctorius. I have been keeping imitators with Suriname cobalts in a 90 gallon for almost a year with great success. Unfortunately, the snails and slugs usually get to all of the eggs before we do, but it is obviously not a breeder setup. The imitators, are, however, in the process of raising a tad(s?) in a bromeliad next to the front glass!
A while back, I even put a newly morphed imitator froglet with a deformed back leg in the vivarium that we had raised from eggs found in the imitator group's (3.1) previous setup. I figured that if it had any chance at all, it would be in our largest enclosure. Needless to say, 6 months later, the frog is in great health and almost adult size. The imitators and tinctorius occupy seperate niches in the environment and even when the do bump into each other, there is no apparent stress.
Good luck. It is definately interesting being able to watch two similar, yet completely different species coexist (given that you have the proper space and experience).