Yes, tets came from dips, and have moved forward as tets-only over many generations. Because they have more chromosomes it is easier for them to mutate faster. So, to bring some of those more highly mutated genes (newer patterns, edges, etc) into the dip line, it might be desirable or useful to revert some tets and bump up the dips a bit. I've only watched the growth and performance of 150 cultivars, almost equally divided between dip and tet, but I haven't personally really been struck by any bigger-stronger-healthier aspect that everyone says is there (and for those where I have the tet and dip of the same cultivar side by side - its even worse; the tet versions have been smaller, less appealing, way less healthy over the long haul) ... I know that maybe its just my 150 cultivars ... but the only characteristic that has struck me is that tets seem to have a bit of edge on somewhat deeper color concentration and more variety in patterns.
And, I've noticed in just my small number of daylilies that many cultivars that are known as dips are really tets now. For example, I was unable to get a dip cross from Dixie Land Band its first summer, so I tried some tet crosses with it and got tons of seedlings. Nowhere is it listed as a tet, so it must have been quietly converted and may now be the predominant form that is being sold. It is not the only "dip" cultivar that I've found to be a "closet tet," and since no one keeps track of tet conversions, from now on I am going to routinely cross all unsuccessful "dips" with tets.
Ultimately I prefer to keep and work with dips, so I think that 1) it would be nice to revert some of the "closet tet" cultivars converted back to their original dip state (made available as both tet and dip) and 2) it would be great to have some of the more highly mutated tet genes brought back to dips to see if they might pop up the colors and patterns of the dip lines any.
