I'm growing Arkin, Kari, Sri Kembangan, Thai Knight, Hart, Bell and a selection from Possom Trot Nursery they call....coincidently, Possum Trot. For me. Sri Kembangan.Thai Knight, Bell and Kari are pretty close in overall eating quality. Hart is a bit strange for me. The ants love them and I have a terrible time with them farming scale on the fruit. I bough my Hart tree about 15 years ago when Excalibur Nursery was hawking it as the "best" carrambola. It was said that it had a pear flavor. I cannot really say that it does to me. It does have a flowery. sweet flavor that is pleasant but, for me at least, a notch or two below the others I mentioned. I also have two seedlings I have fruited with mixed results. I have tried some of the B series and found them decent but not superlative, but have limited experience with them and did not do any side by side comparisons.
As to the origin or history of the Sri Kembangan....just to bring this post back out of post derailment mode, I had always thought that it was a Thai selection. In doing some research, it seems that is, rather, a Malaysian selection. Maybe it originated in Malaysia and was origianlly Seri, then moved through Thailand on its way here and became Sri.