Has anyone put one of these one there boat, are they worth the $

 

If you fish shallow at all, you should consider it in my opinion. Up in the north here, lots of boulders, reefs and other uglies in the water that the keel guard might just save you from putting a nasty gouge in your fiberglass. Also, if you ever plan to beach your boat it will help protect it from getting all scratched up. $100 keel guard is better than a $500 crack or gouge repair. 

If I fished deep water with no obstructions to ever worry about, I don't really see the need for it. I guess it all boils down to how protective you are over your boat.

I self installed a Hamby's "Lite" version ($180 at the time) on my Ranger and I have eased up and beached on concrete ramps with no concerns at all.  I also beach my boat in gravel many many dozens of times a year, also no issues.

Keel guards are cheap money if you have to pull up to a concrete ramp just once.  The edge of the keel is easily damaged, and expensive to repair.  If you never have to pull up, onto a concrete ramp, then maybe it's not for you. 

 

But, as previously stated, you can gently ease it onto a concrete ramp with no worries.  A concrete ramp will rapidly chew up gel coat, especially if waves or a wake are lifting the hull, and setting it down again on the concrete.  It gets ugly in a hurry.

Yes I have and Yes they are.   Be sure to mark the area where it will fit.  Take a Scotchbrite pad and scratch up the area so it sticks well.  Clean the area well with acetone.

 

It is easier to put on if you have someone's assistance and a creeper but it isn't much of a chore.

I just did my Kielshield by myself(PITA), best $ i ever spent on my boat! I beach a lot here in FLs shallow lakes. I got a great deal too online.