Just read that thread, yeah I can see your issue with legato, but that's due to poly multichannel allowing for polyphony on a channel, ie it cannot/does not assume a channel can only have one note... so in this sense I can see the issue for guitar where you want this - you have to assume the channel to be monophonic for this to work.
So if the OP wants this legato handling its not going to work, saying that neither will forcing all notes on to one channel ... so not sure if its a requirement
As mentioned in above post, unfortunately the voice allocation is done in the code generator, so cannot be altered by a patch. No changes have been made in this area.