From an owner of both types...
Hi there
I've owned and flown a number of C15x aircraft over 25 years of flying. Last year I bought a 2002JF. Both aircraft are excellent trainers and reward the meticulous pilot with a great flying experience. I would say that the main differences flow from the JF being lighter than the 152, although the JF's newer design shines through as well. The Tecnam certainly hops around more in gusty consditions but, with good technique, is an easy aircraft to master. Its performance is excellent, even in the hot WA summers. It's a delightful aircraft to fly
The C152 is a heavier and tougher aircraft. The more marginal performance is itself something of an advantage in learning good STOL and related techniques. It's not as hot as the Tecnam in the WA sun but, after flying the JF, hopping into a Cessna is positively claustrophobic. Without LR tanks the range of a 152 is also a bit of an issue in our part of the world.
I would suggest you move over to the JF, and I doubt very much if the transition would be a big deal. One general comment I'd make is that I think the safety margins of the lighter JF deserve respect: fly it by the book and recognize that you'll occasionally leave it in the hangar on days you might have headed out in a 152/172. I do think that if you take the time to master the JF, you will end up a better stick-and-rudder pilot.
All the best, and good luck.