I've never had a drive guard on a trailer before. Can anyone give me the pros and cons?

I don't think there are many cons....except extra upfront cost, and the trailer being longer. I will get one on my next boat/trailer.....it's just good protection. I'd rather have a ding in my steel trailer drive guard than having to replace a skeg or entire drive(s). JMO.

I have heard that they can get hung up if you have to go up a steep driveway or anything like that. They are more for backing up and what not. They will not protect against getting rear ended all that well I would guess. You also have to be carefull pulling away from fuel pumps

The trailers that have drive guards are nice.
Problem I've considered is,
Swing away:
remembering to lock out of the way.
Extra length of trailer making drifting off center while loading/unloading and getting hung up on trailer. Steep ramps would not be a problem.
The solid-non removable guard is in the way for shallow launching and limits you to crane type haul outs.
Makes trailer storage more restrictive.
Working on drives-back of boat is a pain in the neck. Pulling drives, changing props, running on muffs- it's all in the way for easy access.
Constantly tripping on the trailer.
If the guard is totally removable then you have the trailer side extensions in the way.
Pros
Small dings and damage from parking lot rash limited to trailer and not the props and drives. If you back into a spot and miss judge the distance. Drives don't take the hit.

Thanks for your advice. I decided against the drive guard.

Sounds like you are having trailer made. If it is a Myco, consider the bow ladder option. I had some work done on the trailer and had them add the ladder and a second spare tire. Both have actually came in real handy.

Andy