David, I am just about ready to put my Agusta in the air (hovered it around the yard yesterday), and I'll put in my 2 cents on MB heads. You probably have as much or more experience as I do, but here goes.
First, the MB heads are more sensitive to phasing and pitch than the flybarred heads. There is a tendency to 'balloon' coming out of turns and when the wind is up. A couple of methods are used to counter this: enough weight in the nose to allow the rear of the skids to come 3/4 - 1" before the front of the skid (when picked up by the shaft/centerline & depends on the model); the Vario MB Gyro or something similar.
My opinion is that the MB gyro increases the complexity and failure potential. I bought 2 of these things when they first came out and tried many times to get the friggin thing to work right. I never could, so I sold them. That said, the difference in how Gary Saia's 412 (looks familiar!) flew in Dalton with the Vario MBG compared to a couple HH gyros (not in HH) was night and day. The Vario MBGs made it look solid. The phasing thing is quite interesting and I am playing around with my 10X built-in electronic phasing. Joe Howard started me on using this, I think back when I had the Tiger. This is starting to come together for me and I like the way I can do minor adjustments without changing the mechanical setup (which, by the way are vertical rods from swashplate to grip balls). The VBMG also has this capability.
The 2-bolt blades also help in controlling the lead/lag, making it pretty much non existent. None of the 'fixes' are going to make a heli with a multiblade head fly just like a flybarred model. You just have to fly the thing and get used to it. I have the tendency to fly mine fast (not good) because I still tend to push forward when the thing balloons instead of dropping collective (what can I say?). I have flown with VMBG and without, using the 2-bolt blades, and if set up right fly almost the same. Oh yeah, one more thing is that the VMBGs don't like digital servos....They buzz and eat up (along with the VMBG) a lot of battery power!
The Agusta is currently the last of my Vario models (Benzin powered), and I think I'll keep it. I like the straight forward TR setup, lean look and the MB head looks and sounds cool. The Tiger was a real pain to work on... very tight space and a heavy machine. Russell Matteini put together a 5-blade Hughes 500 (Vario #9005). He never flew MB heads before, slaps the thing together and proceeded to fly the pants off it! There was a short learning curve on the head speed and sound (along with the ballooning tendency), but he seems to have that under control now and will be painting that up soon.
I'm waiting to see a 5-blade turbine Hughes... That would be too cool!