Harry Is quite right, I hedged my bets and got both. I have decided to dedicate the Multiplex to my very large fleet of gliders and electric gliders. The Jeti will be the weapon of choice for the Jets.
Having flown both, for the the ergonomics of the Multiplex has the edge. The sticks are fabulous. For me the fact that you can have switches in so many different places ensures that even with gloved fingers (on British slopes in winter these are de rigueur) I can reach every switch and slider with ease. The Jeti is good from this perspective, but not quite as good, although with the planned rearrangement of switch positions this will improve.
The Jeti trims are still not to my liking (but somehow better than the old MPX REP) but the auto trim is fabulous. The displays on both are good, although the planned upgrades that MPX have in the pipeline will provide the ultimate in user adaptability.
I range checked the Jeti on Sunday and got the same superb range as the MPX have always given. Both best in class.
When it comes to the software, the MPX is easier to set up but less familiar. As a 4000 user you will find the Jeti makes you feel right at home. The Jeti is way more capable than the MPX at this moment in time.
TBH, there is not much in it. I set my ES up on the MPX first and then on the Jeti. It was slightly easier on the MPX. BUT, when it comes to comes to programming the much more complex F14, the Jeti will take the honours by a furlong. MPX may well catch up with software updates, but I think it will take some time.
BR

John