Have you tried any of the hardware synths listed on the Recommended Sounds page? Granted they are mostly multi-timbre synths and not true MPE, but I believe the MicroMonsta is MPE.
Yes it is true that synth makers are still catching up to MPE and that hardware synths are always behind software synths. That’s in part the cost of being on the cutting edge. Many buyers of synths barely know what a note is, much less polyphonic expression.
Another important point is that MPE is mostly important for polyphonic pitch bends, which aren’t even used in most music. Keep in mind that one-channel synths still give polyphonic pressure, and LinnStrument’s smart MIDI prevents any problems when performing poly bends on one channel. Note that Jeremy Cubert’s video on the LinnStrument product page doesn’t use any MPE synths.
The more important issue in my view is expressive presets, that take advantage of LinnStrument’s 3 dimensions, as for example Sample Modeling’s software instruments do. Again, in this area hardware instruments will always be behind software instruments.
I hope this is helpful.