Just for another consideration for a nice mic headset to use with an arranger and VH, Roland bundled the Hands-free microphone DR-HS5 with the VP-7. (See details in link, plus nice video near bottom of page). The VP-7 is discontinued, but probably find the DR-HS5 on eBay.
http://www.musiciansfriend.com/pro-audio/roland-vp-7-vocal-processor#productDetailI have used the Roland DR-HS5, but I personally do not like the limitations of a mic set at a fixed distance. I prefer using vocal and mic techniques with the freedom of a standalone or studio quality mic.
Strange that there are no Roland VP-7 videos demonstrating the fantastic Variation Mode (Roland Variphrase technology), that in my view rivals any new VH technology out there, including anything from TC Helicon. Roland further developing this VH technology and adding it to a top end arranger would make for one nice arranger keyboard.
Marcus