Thanks Jonny. Am not savvy enough myself to use those alternatives to the next release, but no doubt they'll be useful to others watching this thread.
We're currently engaged in an overhaul of our Tiki site and this week I want to make a new top navbar using the Structure plus Bootstrap plus Smartmenus method. It's a big site and we'll need a lot of dropdowns. I might be back with a new post on that if I hit any snags. If it goes well, knowing how to delete the old menus afterward has removed a major stumbling-block from the process and for that I say once more, many thanks.