When I mentioned to the owner of Jagpro that I was using the J-Gate to down shift fairly often, and I do not get it anywhere near the red line when I do, he gave me the warning. I brought up the subject because over the past 4 months when I did the down shifts the car went into limp home mode 5-6 times. All I had to do to get full function back was to turn off the ignition, and restart the car and full function was restored. It did not matter if I restarted immediately or waited a few seconds.

What do you think the problem is?

it depends WHY the car went into limp home. it comes out with key cycle cause if it doesnt see the same fault it retruns to normal. You need to duplicate it and diag why under failure. I would suspect adjustment/or selector switch failure

I think our Jag Owners assess J-Gate so special .I really don't think J-Gate differs to GM Trannies or W140 MB S Class's gear selector .
Why I am saying is this in J -Gate we have some numbers that inhibits to go upper gears than selected ones . I mean if you select 3 , you will not use 4th gear
Same logics runs in GM and MB too . If I happen to select 3 in 4L60E , maximum gear speed is to be 3 not 4 .
Using 2-3-4 is useful if you climb up the hill or come down the slope . Other than that D should be default gear in normal driving conditions but everyone is entitled to their opinion

Wow mixed emotions here guys, Long tome x-type owner, short time poster. I love to use a car for what it is worth and get a thrill out of using the j-gate. I shifted through it HARD when test driving my newest X-type to test the infamous tranny. Mine seems to work great. I guess I look at the x-type as a "baby jag"; fun and sporty but not a real sports car. I use the j-gate now only when cruising the curvy, hilly, back-roads of Clifton, Va. It is great for keeping consistent speed, increased braking ability (Engine compression assisted) and a lively throttle response, however I know that every time I use it I am doing my transmission more harm than regular driving. Its like this, no matter what brand, what type, what model, what it is used for; the harder you work a vehicle, the more problems you will have. Jeeps run great, until you actually 4-wheel them. Yes they are "built for the off-road" but I know from many years of experience, if you take them through mud, up steep hills or in the mountains or desert, stuff WILL break. I have an F-350 quad-cab FX4 Lariat PowerStroke Turbo Diesel. The thing was BUILT for towing, but I know for a fact that with all of the towing I do, (Tractors, Bobcats, SteamRollers, Paving Machinery) it will not last as long as one that is driven around by someone who does not tow and who does not rev the engine high. The 350Z by nissan, a real sports car; If you are putting the hammer down all the time you will, blow a turbo, smoke a transmission and destroy the engine. Its just reality. The harder you use a mechanical anything, the shorter the life.

Just my 2 sense!