I put one on prior to the start of the season. I like the fact that I can lock up the rod and reel I bring as a back up.
I have had 3 rods and reels in the box and feel that you can fit 4 conventional setups at once but if your using larger spinning reels like a 8000 or 704 you will be hard pressed to fit more than 2 rods and reels in the box. I generally colapse the handle on my spinning reels which gives you more room.
I got a fairly good deal on mine via ebay. I paid $111 with no shipping charge. So if your interested you might want to take a peek on ebay.