you have to ask yourself the question first, what do you need the camera to do?
If you need Steven Spielberg quality and money is no object then by all means go for the Go Pro 4
But..........
Apart from some flashy extra bits like being able to record in 4K (you need something that will display it back at that resolution to be able to benefit from it) or super slow motion stuff that most people never ever bother with after trying once, there is very little difference between something at the top end like the GoPro and right down at the cheaper end like the SJ4000 or it's even cheaper Chinese copies (which out perform lots of the inbetween market).
For what it's worth the only variations in picture tend to be a slight variation in colour or brightness and the clarity when the brightness of what is being filmed changes quickly, but again ask yourself where you are going to actually view what has been recorded, most tend to throw it up on youtube which will compress the video and you never truly get what you have recorded then anyway.
I ended up with a Drift Ghost S as at the time it was ?100 cheaper than the GoPro 3 and could be picked up cheaper from FC-Moto.de than anywhere else in the UK, It is also a bit more streamlined than your average GoPro unit (although it is about the same size) and fits nicely on the side of my helmet or on the side of the fairing instead of sticking out like something from the top of a Telly Tubbies head.
But realistically for what they still cost, I could buy 3 or 4 of the SJ4000 units and stick them all over the bike, or at the very least have one at the front and rear for and still be paying less than half of the cost of a Drift or GoPro and it would also come with far more attachments.
I wouldn't be out of pocket as much if I lost it either.
Spending more on action cameras definitely doesn't always mean you are getting the best quality, particularly when paying 200% more may only mean you are getting a camera that records a 5% clearer picture.
