we have steep ramps too, never caused a problem for any of my boats. Bunks will last around 4 to 5 yrs before needing any work. you can drive on either trailer. I just like less maint. on the trailer so i go with bunks now. i've had 3 or 4 roller trailers. i'll get some pics for you of mine sitting on it's bunks. look in my gallery you'll see my V20 on the trailer. Look at the links at the bottom of my reply and see pics of all my boats on both types of trailers.
Here's a link to several V20 pics
http://www.boatshots.zoomshare.com/1...t%20V20%20Boat