If you are thinking with going with midi to trigger vocals you may want to look at the Harmony M at TC-Helicon.It is made for keyboardists but it could care less if it is a live keyboardist or a sequencer. http://www.tc-helicon.com/products/voicetone-harmony-m/ It allows you to hook up midi. Like Mac has already said there are cheap solutions to the USB to Midi problems. While the VL2 gives you all of these options I definitely understand the $$$$. I guess the questions I would ask myself if I was in your boat (assuming you like the vocal results)are:

1. Will I always be running some type of track behind me when performing allowing be to send chord changes to the device?
2. Do I ever have the need to play just acoustic or electric guitar and want vocal harmonies.

If the answer to number 2 is yes, then you need to look at the manual setting on the Harmony devices. I know the Harmony G has a manual set up that lets you set the key before you play. It will then create simple harmonies with notes only from that key.

If you can find a store to play around with one of these that would be good but my experience is that they normally are not on display to provide that luxury.

Terry

TerryB

Windows 10, Dell 8700 XPS i7, 12MB Ram.