[martingitdave]

You're going to get a lot of recommendations. I see you have three potential paths.

1. Solve your stated problem using the Yamaha system you currently have. The benefit is that you already have the vocal and guitar processing you need and you're satisfied with the PA performance. In this case, you can purchase a small quality wedge monitor and go on about your business. This costs a few hundred dollars and will solve your stated problem.

2. Attempt to consolidate your guitar and vocal effects processing by adding a multi channel amplifier as your pre-processing unit and then send that DI signal to your yamaha. I think this could work, but I think you just cause more trouble. You'll probably still need your effects unless you get a Line 6 or amp with acoustic modeling built in. This will cost $1000 and might not solve your stated problem without adding complications.

3. Upgrade the whole system to one of the solo artist systems that performs as a capable house system AND a monitor by placing it behind the player. Fishman, Bose L1, JBL, etc. These can be used with your current preamps and vocal effects. You simply replace the Yamaha system. You can also buy the more capable systems like the Bose with the T1 mixer that will replace all your gear and pedals. This will be a $1,000 to $3,000 endeavor depending on the amount of power and features you need.

To me, it sounds like you should look at a quality wedge monitor and enjoy the system you have, unless you want to jump to no 3.

EDIT: I see you already made your decision.