I have had the e-Fin from Jaykay for around 2 years. I use it for my SUP and also for my hybrid kayak Nortik Scubi 1 xl. On this inflatable kayak, which is quick and easy to take with you, I have attached a bracket for the e-Fin so that I can take it on other trips. It works great and the fin takes up very little space in your luggage. You also don't need a cable and extra batteries, as with many other electric drives for boats or SUPs. The additional function that only provides support when paddling is a really great and I think unique idea from Jaykay. It's like riding an e-bike. The performance is good for the SUPs and also for my kayak. Es is not a racing boat, but that is not the purpose. The range could be a bit longer, but with a larger battery the handling would not be as good. I use the kayak for paddling, occasionally take the e-Fin out just to enjoy the surroundings and have also extended es for sailing. The e-Fin was a great addition to this multi-purpose boat. Even when sailing and the wind drops. Es once had a problem with the e-Fin but Jaykay replaced the fin without any problems. That would usually be a problem with some other suppliers from C... etc. It's better to pay more, get good quality and then also an accessible service. 

A purchase is recommended.

P.S. I'm currently building a holder for the e-Fin on my beach catamaran. I'll be testing this in the south of France at the end of April. The aim is to get back to shore in calm conditions or in difficult harbor situations (wind/many surfers etc.) with the "emergency drive". If es works with the Bluetooth connection, I can send it to you.