I think it's a hard choice now between the ES-3 and GT-1000 Core in the Boss world. If the Chorus , phaser and Flanger options were better on the GT-1000 Core or ES-3 I'd probably be tempted. The Source Audio gear really does sound great and it puts other marques into perspective. I do a lot of home playing with headphones and the SA gear is in the same sonic league / processing capability of my Eventide H9's and EXH Hog2. The Boss stuff sounds good, but the modulation has a sort of digital sound to the effects that I can't seem to dial out.I actually used the loops a lot! I put my Aftershock in one, the C4 in another, and the lunar in the third loop. The MS3 doesn’t have the moveable loops though, so that was a downside. I normally didn’t use the built in effects, but occasionally I would them (like an extra chorus on top of the Lunar).
I'm only using my ES-5 as a master midi controller, patch hander and a few patches where I change the pedal order. I'm thinking of getting a Spectrum and moving my C4 later in the chain...so it's becoming less of requirement to move my pedal order around per patch. I might get a smaller Midi controller...or I might save a few Shekels and leave it as is...it's working well.
I think if Source Audio wanted to make a Soleman II, the Boss ES-5's feature set and size would be a good template to start. A few extra loops and stereo would knock it out of the park. However, I'm not sure it's a direction SA want to go in.