I bought this with the intention of using it to control my ADA Viper. It wouldn't switch the channels in the Viper, but it works well with my Peavey mini head. Harley said he was wondering about this unit, so I thought maybe some other folks might wanna get the lowdown on it;
It is very small. Very mighty. The only pedals I add are a TCE Mojomojo for my 'classic rock' tone (the Peavey is too brutal for that), and a EHX Pitch Fork. The pitch fork is a great whammy with an expression pedal and the octaver is better than the MS-3.
It has three effects loops, but you have to dedicate one to the amp. So, I put the amp in Loop 2, giving me the option of adding something before or after the amp. You can move all three loops elsewhere in the effects chain, but the 3 stay together as one. You cannot rearrange the loops themselves.
There is a proprietary editing app that you access via USB. It's worth the price of admission by itself, I love that app. Like other BOSS multi effects, there is a Manual mode that allows you to toggle between presets and stompboxes. You're using presets until you hit the Manual button, then you have individual stompboxes. That's pretty nice when you just wanna add a delay to your solo or a nice rotovibe to your clean patch.
There are two 'control' IN jacks and one control OUT. The control OUT switches the channels in the amp. One control IN has a Boss FS7 footswitch to use as a bank up/down...the other has a 1-button footswitch connected & I've set that to be my solo boost. As a backup, you can set each preset button to have another function, like a solo boost. So, let's say I select patch 2, if I hit the 2 button again, it activates the solo. To deactivate it, I either hit the 2 button again, or select another patch. The only drawback with using the patch button as a solo boost is if you're in Manual mode, you need to get out of that mode to access the switch again.
Having used the Boss GX-700 for so long now, the FX layout on the MS-3 is very similar and familiar. Some of the effects are very similar too. While the MS-3 is not an Eventide or EHX type quality, it is a great little workhorse for a gigging musician. It has what you need to cover a lot of bands in 4 hours, won't break the bank, and takes up very little room.
The one thing I haven't figured out yet is how to make it send midi changes...to use as a midi footswitch if I wanted to...but I have a midi footswitch already, so it's not a big priority yet.