Recently bought a 70 lb Maxxum for my 17 ft Laser Bass boat and I am wondering what problems I will have since i purchased a 52 inch shaft vs a 42 inch. What would be some advantages and disadvantages?

If you set the motor too deep, you may run the motor into the bottom sooner than you might like to. Raise the motor up, and the head may get in the way of your fishing. 

I run a 60" on a Crestliner CMV.

It'll be OK.

Scott F gave you the disadvantages. One advantage is in rough water you can set it deep enough to keep it in the water. This can be a big deal when fishing in the wind.

7 minutes ago, K_Mac said:

Scott F gave you the disadvantages. One advantage is in rough water you can set it deep enough to keep it in the water. This can be a big deal when fishing in the wind.

This! I have the short shaft and WISH I had bought the mid-length (52). Its just fine for normal conditions, actually perfect. but in rough water or when a cruiser comes by me I can't control the boat with the prop flying in and out of the water. 

I've had both and prefer the 45". I have a bad habit of smacking the trolling motor with my rod if it's very high out of the water. 

I tend to agree, if set too deep you could hit bottom and possibly damage the trolling motor foot or a transducer if you've got one mounted on the trolling motor and if it's too high, it might get in the way and looks kinda weird in my opinion,  Not sure what the shaft is made of on your Maxxum but you might be able to shorten it yourself.  I have a MInn Kota with a 60" shaft on my bay boat and luckily, it's the perfect length but I bought a Triton bass boat that had a Minn Kota with a 52" shaft that stuck about 3 feet above the bow.  It looked like a light house and got in the way when casting side armed under docks, etc... To make a long story short, all I had to do was remove the  head from the trolling motor, cut 12 inches off the shaft with a hacksaw and replace the head.  Now it's the perfect 42" shaft.  It's a simple process that took all of maybe 30 minutes to do .  The hardest part was getting past the thought of cutting a foot off of a perfectly good $1,200 trolling motor.