I have a tilt bed trailer that I use to transport various stuff, including a motorcycle and lawn tractor.
Driving something up on it can be tricky. You have to either block it in the tilted position, or be ready to deal with it slamming back down with you and your equipment on board once you cross the balance point. If you don't block it, you need a second person to hold the bed tilted for loading. If you block it, and it has a wood deck which happens to be wet, say from dew or rain, it can be a real interesting ride. /forums/images/graemlins/shocked.gif
The last time I tried to load my motorcycle that way, all I did was slide back down. Since I didn't have anyone around to lend a hand, what should have been a simple job became a monster chore.
If you don't block the bed and have long wheelbase equipment to load, under the right (wrong?) circumstances you may find the bed starts back down before the rear wheel(s) get on board. This can lead to damage or injury.
Tilt beds can also be pain to hang a license plate off of. You can't mount it across the back, unless it has a removable gate, as it will get bent the first time you tilt the bed.
My trailer did not come with a license plate bracket, and I found there was no place to put one on the rear without blocking part of the bed or flattening the plate. I ended up fabricating a mount for the top of the fender. A license plate must be mounted on the rear of the vehicle in some states, although I doubt that many cops would issue a ticket if it wasn't.
I would advise looking carefully at the trailer to see how high the bed is when it tilts--and if it's in your comfort zone. You may also want to consider how much effort it would take to tilt and block the bed with your load in place, should you ever need to do that. A 16 or 18 footer with a tractor on board might require quite a bit of muscle.
You might also want to check out the tongue length. For some reason, most of the tilt beds I have looked at have had short tongues, which makes backing more difficult.
Hope some of this helps.
SnowRidge