Mikey don't give up on sending vocals through the Tyros. The feedback is not generated by the Tyros pass though. It will be generated from ANY mike under the same gain staging.
They Tyros has a great noise gate. Using that with the compressor should eliminate standby feedback issues. I have found using them will reduce feedback....Also reverb can create feedback issues as well. Mess with those. At 8 feet you should not have feedback issues,

We did a show last weekend, where there were two L1 systems and I was no farther than 8 feet in front of either tower which were 12 feet apart. The vocals were loud and we dialed in the EQ and had no feedback issues going direct using a Yamaha MG mixer.

If you still want an outboard reverb, try the nanoverb from Alesis. http://www.sweetwater.com/store/detail/NanoVerb

[This message has been edited by Kingfrog (edited 05-23-2009).]