Even though MPE is a new buzzword this idea has been around for a long time, it’s basically midi mode 4 omni off/mono which has been used for years for midi guitar. See http://www.philrees.co.uk/articles/midimode.htm for a very good description of the MIDI channel modes.
A plugin that has each of it’s voices controlled by a different midi channel would not use any more CPU than a plugin that provided the same voice count but is controlled by a single midi channel.
If the plugins voices cannot be controlled by different midi channels the trick is to split the midi channels up and have multiple plugins each listening to a single midi channel, so for a guitar you would need 6 plugins, one each for channels 1, 2, 3, 4, 5 and 6, this then uses a load more CPU than just having a single one.
Edit: I have a linnstrument here and it is easily one of the best buys ever, a fantastic piece of kit. Highly recommended.