I tried them on my Mossberg 535, and the gun ate not one but two of them, so I am not a fan at all of them.
As far as a comparison to a FFII, there is simply no comparison. If you are looking to go with a red dot sight, a Burris FFII, or FFIII is the way to go. Great company, superior customer service, and a very well built product.
Don't bother with the cheaper optics like a truglo. If you can afford one, pick one up. If you can't afford the Burris, than my next suggestion would be a Mueller Quick Shot. Very rugged with 4 reticles to choose from, and it is more than half the price of a FFIII.
Having shot both sights, I would go with the Burris. JMO.
