I just had a chat with my Smiss contact. She told me to wait after CNY to get the FM5-Pro because right now the samples they have are pre-production and the PCBA has still some stability issues. I would advise you guys to wait some more unless you really want to beta-test.
As for the battery replacement, I'm waiting for more details but I'm afraid it will be more complicated than expected. She mentionned having to write a program on the chip after the batteries are replaced, so I suspect some data would be lost in the process, like for instance the calibration data (it was the case with another portable vape, I just don't recall which one)
In all cases, due to the possible danger involved, Smiss as a company does not support DIY battery replacement and she strongly advised me to warn you about it. Don't put your house on fire please!
@Pipes : btw the original cells are 2600 mAh.
There are other portables in this price range (as low as $45 delivered) with step by step temp control.
Which one(s) are you thinking about? The HD has only 5°C steps and will be priced probably equal or higher than the FM5P.