We had to discontinue the ProLite 35 because Grafalloy / True Temper did not want to make it for us anymore. It was exclusive to us and the quantities sold had decreased over the last few years. It had a good run, to say the least. The product was over 30 years in the market, maybe longer. Was the first really lightweight graphite with a very stiff tip. Interestingly, the Pro Launch Red is similar. It is slightly stiffer in the tip than the ProLite, but slightly softer in the butt end. They are very similar in profile in the mid section of the shaft. The ProLaunch Red would be the closest thing to the ProLite you could try.
As far as the heads, both are outstanding, but I know that will sound biased coming from me. The advantage of the KE4 TC is the adjustability. The ISO-T is a rounder profile and manufactured using a very unique process. Ball speeds off the face are similar, so no performance difference there. In my experience, and I have played them both, the ISO-T produces a little less spin. That being said, I play the KE4 TC now and did all of last year and in the the setting I have (which is the lower loft setting), the spin numbers were similar when using the same shaft. Performance is probably not going to be the deciding factor for you, as if fit properly to your game they both should perform at a high level. The adjustability and the cosmetic is what what made me settle on the KE4 TC as my primary choice. I have a couple of shafts I like and depending on the day, the course, the wind, I can easily switch the shaft in the KE4 TC to achieve the set up I want that particular day.
Hope this helps.