If you don't want to read the review below and just need a quick hint - the DRIFT 170 cameras are AWESOME - the HD170 is the best out of the 2 - would recommend the HD170 if your budget can stretch to it - you will not be disappointed...
The longer version.
Having tried bullet cams previously, I was looking for an ALL IN ONE camera to go on my motorbike - bullet cams are great, but I got tired of the amount of cables and the the external recording device you have to have.
So brought this to go on motorbike for training purposes, and the first thing to say is that if you can afford the HD170, it is well worth the money.
I have both the X170 and HD170 - although the X170 is great (SD), expanding the picture size on full screen to a PC or TV, you do lose definition. Unlike the the HD170, the video quality on the HD170 is outstanding, even at full screen.
As I have both I might as well give the pros and cons of both:
Video quaility is as you would expect from HD - outstanding - you can record in 720P, 1080P or SD (MOV format only)
The intergrated mic is very good and the sensitivity can be adjusted to low, med or high
Battery life on the standard supplied rechargeable Li-ion battery is very good - have managed about 2.5hrs
Has a good integrated LCD screen and speaker for playback (about 1 inch diagonal)
Has got a x4 digital zoom in 720P mode - the X170 doesn't have a zoom at all
The supplied mounting options are varied and great - I mounted the camera on the wing mirror stem (BMW GS1200) using the supplied handbar mounting attachment and a bit of rubber padding (rubber padding not supplied) - fitted and working with 5 minutes.
One of the BEST features of the camera itself is the lens can be rotated up to 300 degrees - so it doesn't matter where you mount it - just twist the lens to offset the angle of whatever you have attached it to and the picture will be vertical
NO EXTERNAL cables needed - unlike some bullet cams which which normally require wires to external power source and mic.
Supports up 32G SDHC cards - which provides approx 6hrs at 1080P or 9hrs at 720P.
The other most important feature to me was the wireless stop/start remote control - making start/stop so easy (especially on a motorbike)
Physical Size - the pictures are a little bit mis-leading - the cameras look massive, but they are not - about 4 inches long, 1 inch deep, 1.5 inches wide and very light (138g)
Accessories - good selection available such as Extended Battery and battery charger (see cons)
Battery and SD inserting extremely easy (compared to the X170, which is very difficult)
Can be powered by external cable while mounted via a cigar lighter type charger (sold seperately)
Water resistant (up to 0.5 metres apparently) - so no problems in rain or snow.
Only one real niggle, that is the supplied battery has to be charged via a SUPPLIED USB cable while it is in the camera itself - there is no supllied battery charger. As I say just a niggle, as I have brought an external battery charger and some spare extended batteries.
X170 SD PROS:
VERY WELL BUILT - my one came off my motorbike at 55mph (my fault, I hadn't attached it correctly) - it went bouncing down the road for some distance and got run over by a car - after I had picked it up, turned it back on, it worked perfectly - just a few scratches (luckerly the lens was not sratched at all). I haven't subjected the HD170 to the same test (yet), but am sure it would also survive.
The PROS for the X170 are really the same as the HD 170 except obviously the video quaility is not HD. Video quality is fantastic providing you don't view in full screen mode.
It can record in AVI, MOV or MPEG 3:2 or 4:3 format.
Uses standard AA batteries - so as long as you have spare ones, you will never run out of power.
The main issue I had with the X170 is inserting the 2xAA batteries or SDHC card - it is quite fidderly to close the compartment once the batteries are in.
So overall, if your budget can stretch to it, go for HD170 (but would recommend get a couple of spare batteries and a charger).
The standard X170 is great if most of your videos will just be seen on a PC or YouTube, would not recommend for view at full size TV size - but the X170 takes standard AA batteries (although a bit fidderly to fit).
There will be better cameras out there with more features, but this is the best I have come across for an all in one camera used on motorbike at a very reasonable price.
Hope this helps someone.