I have not used any Lightforce brand lights, but I've installed Hella 500 foglamps and KC Daylighter Off Road lights, and also Wal-Mart low profile fog lamps.
The KC Daylighters are 100 Watt 6 Inch lights which look equivalent to the LightForce 170 model. However, I noticed that the 170 is around $200, while the Daylighters can be bought for less than $150. LightForce looks like quality lights, but KC has been around for 30 years, and makes similar products for less.
Also, 6-inch lights are BIG. I have no motorcycle experience, but perhaps a smaller light, like a projector beam type, may be more suitable.
Have fun,
Brian