How comfortable are you with overrides?
Here's what I would do:
Create a menu module that shows the menu levels I want displayed in my breadcrumbs.
Use joomla's native breadcrumbs.
Create an override of the module (need instructions?).
At the bottom of the ul in the module, call in the menu module previously made. I'm not sure if loadposition will work here, but Modules Anywhere will for sure (that's a No Number extension).
Then just style it up. Hide the menu module until the breadcrumb is hovered over, style them as desired, whatever works.
Why this way? Because you have 100% control. There's nothing more annoying than going through 30 plugins only to find each one doesn't quite fit the bill. Plus, the less plugins, the better. I prefer to use native joomla whenever possible.