MIDI Guitar 3.0.66 was just uploaded with a real guitar sustainer as the Sustain module works on guitar sound (when Guitar Mods are installed and enabled). You should generally use it with Unison and there is also a new Swell module that also works on guitars.
Also, now Mods can be combined by simply cascading more Mods. This way they morph into each other, vastly expanding the space for finding sounds with just a few building blocks. So for example Cello Mod => Mellow Mod => Synth Mod becomes a “synthy mellow cello” 
The morph parameter sets how much the instruments character that is present over the previous ones and each of these characters can be turned off or on with the main switch.
Unlike what you would expect, such Mod cascading has zero quality, performance or latency degrade, but of course the Mods themselves, as building blocks, still need a bit more refinement and expression. But that’s for later.