sorry -- I've never used any Rode mics
How's the variax thing working out for you? I would think you'd want to retain the option to record your real acoustic (in which case you'd want to hang on to the KSM27 until you'd replaced it with something better for acoustic recording), but I'm just guessing -- never used any Line 6 stuff either, to tell the truth.
So why am I posting? (hmm....) I guess I want to underscore what the other folks are saying -- if you need a better vocal mic, consider that in isolation, which is maybe what you're doing. If you want suggestions in that area and you can provide a link to some recent recordings of vocals that you want to improve, that would help the group zoom in on something. Depending on what you need/want, the answers could be all over the place in terms of mic types, brands and prices, and potential impact on the rest of your signal chain components.
I've got a KSM27, too, and I don't use it for much -- but rather than sell it, I prefer to save up and just buy more mics - that way I can pull all sorts of stuff out of my mic "locker" when the need/whim arises