I'm based in the US now and manage a 1980 (or is it '81? Can't remember) 'Lock & Key' Panther Navajo from Mike Jones. I also fly a 1974 Panther Chieftain (not a M.J. one) and a 1979 B200 Kingair.
The MJ Navajo is nice. From MJ it came with:
Cream & blue leather interior. Pretty standard MJ interior. Look at any of his ads & you'll see what you get. Wing lockers, 7 seat club interior incl. potty. Aft partition with power outlet for electric razor, ice & drinks cabinet. VG kit with incr. MTOW.
Avionics:
Garmin 530
Garmin 430
Garmin 330 TXDR
another garmin TXDR (not the 330 mode S type, but can't remember the model. 228?)
Avidyne 500 MFD
Digital fuel flow
Glass HSI (Bendix/King thing. Quite nice)
Colour radar (displayed on the MFD)
Stormscope (displays on both Garmins, the MFD & HSI)
Mode S traffic uplink (also displays on both Garmins, the MFD & HSI)
Known icing
full co-P panel
digital ammeter/voltmeter for L, R & bat buss
O2 to each seat
XM weather (shown on the MFD)
KAP200 AP with YD.
Garmin audio panel
Intercom throughout incl separate pilot & pax audio input. I can listen to music independently from the cabin.
It also came with lighweight, high RPM starters and a scissor link quick disconnect kit. The nosegear disconnect is very handy if your plane gets towed a lot. It eliminates the nose gear towing turn limit. I've lost track of how many PA31s I've seen here with the **** knocked out of the nose gear casting from towing.
We've since added a JPI EDM.
Performance:
Rich of peak: 190-195 kts @ A100, depending on weight. FF 42 GPH (US gal. of course)
LOP: 170 kts @ A100. FF 28-29 GPH. This aircraft's flight manual authorises 50 deg LOP but I wasn't willing without being able to monitor TIT & each cylinde'rs CHT, EGT.
Nices PA31 I've ever flown. It's BEW is heavy for a Navajo though: 4750 lb vs 4550 lb for another one of similar age I used to fly.
The Chieftain is is also a Panther but not an MJ one. Not anywhere near as nice. Also an older airframe so suffers the lower gear speed limits & max 25 deg flap. It has a VG kit too so increased MTOW. Chieftains also get an extra 50lbs in the nose locker.
Typical 'quick upgrade' avionics: Slap in a Garmin 430 & TXDR. Still has a standard '6 pack'. Not even a HSI. Interior not too flash (1974 ugly) but serviceable. Bought quite cheaply though so a planned upgrade throughout will still be cheaper than one from Mike Jones.
Performance: 170 kts @ 42-44 USG ROP.
Overall: The MJ 'lock & key' aircraft are really nice but you pay through the nose. You really are paying for a nothing else you *need* to do aircraft. Recent ones include an EDM so even that upgrade isn't needed.
The Navajo - with VG kit - has a great useful load. It's not a short field aircraft though. For that you need an Aztec or even an Islander for really short strips.
If you go for a PA31 make sure you get one *with* the wing lockers. Not all of them had them (they were a factory option). You'll lose a few knots cruise speed and not get quite as much extra MTOW with VGs but the versatility is worth every bit. Especially with golf bags or fishing rods.
Seating is more comfortable in the Chieftain for pax & crew.
Pax: Even if the full 10 seat interior is fitted you can still do club seating. Most times push Row 3 back to R4 to make lots of leg room in club but still have the option to use the R4 by moving R3 forward a bit.
Crew: Navajo's are dreadful for leg room if you're tall. I'm 6' and am cramped in a Navajo. Not so in a Chieftain. I even need to move my seat forward, unlike a Navajo where I can't get it back far enough for comfort.
As rule of thumb the VG kit gives you two extra bums depending on bags & obesity. A Navajo goes from full fuel/4-6 POB to full fuel 6-8 POB. Chieftain goes from full fuel/6 -7 POB to 8-10 POB.
The Kingair 200 is a different class entirely. Operating costs are triple the Chieftain. Its interior is even nicer than the MJ Navajo. Of course performance is rather better. It would want to be for the cost! 120 USG for the 1st hour after take off/90 USG subsequently. Never mind the insurance and recurrency costs.
Still, it's nice to be doing 260-270kts at FL250 in pressurised comfort above most of the weather with upgraded avionics.