
I've yet to meet one, they are not a common cross even with the wealth of such crosses that I see on a daily basis as a trainer. So you may struggle to find anyone to share experiences, but I can give general experience based on all of the crosses I've worked with, including numerous ones of both those breeds.
In any case, Tommee's post is excellent and her information is just as important as experiences of owning and raising them - health plays a HUGE part in the life of a dog and in how they behave, and finding a pup of any pure or cross breed from health tested parents is indescribably important for every aspect of owning and living with that dog. I cannot count the number of these small crosses I have been to see who have luxating patella, for example.
I have met many cavalier crosses who still make noises in line with dogs with restricted airways, as quite a lot of cavaliers have, so there's no guarantee on that front. And many jack crosses with the patella issue so again, no guarantees. I've seen dodgy backs, front and back legs, and temperament problems. The particular cross you mention is also a high drive terrier crossed with a spaniel, which can result in a difficult to handle and manage dog - not always, it depends what gets passed down from the parents but the problem with crossbreeds is that it's a complete lottery!
If health is what you're looking for then whatever breed or cross you go for, you must buy one from health tested parents that are in sound condition themselves (a dog with no luxating patella could still have badly shaped front legs and not be suitable for breeding) and your chances of finding that for a "cavajack" or almost any cross is small. There are however a decent number of cavalier breeders breeding only from fully tested, healthy dogs, trying to undo everything the greeders have done to the breed.
You may luck out, find one and have no problems but again, it is a total lottery unless you stack the odds in favour of health (and temperament).