I've got a group of guys I do a lot of my off road riding with that ride 400EX Hondas, as do I. When we ride we ride about 50% off road and 50% on road. We on the 400EX's don't even like riding with the 4x4 guys (2006 to 2011 bikes) because they are so slow and don't go near the places off road that our 400's do. Maybe its just the riders, I don't know.
About a month ago a group of us went riding. I was on my Polaris 3-wheeler, we also had a Yamaha dirt bike, 2) ATC200s, 250SX, Honda 650 Rincon and a Yamaha Grizzly. We went through an old tractor creek crossing that was washed out pretty bad. The exit side was sand, fairly steep angle but only about 5 foot tall. We all we through no problem other than the Grizzly, he flipped over backwards and trashed his racks then went home. I know that was lack of riding skills though.
In my opinion the 400EX is the greatest 4-wheeler ever made. True you can never get one to run like a 450 but they are freaking indestrucible where a 450 is real high maint, I bought a new one and so did a bunch of my friends. My brother has changed about 8 Honda 450 crankshafts, junk. Plus I think the 400 handles better.
08 Outlaw 525s
07 CRF70
04 Harley FLHRCI
04 TRX90
03 XR650R
03 400EX- XR650R engine
02 XR100R
01 Banshee
00 XR50R
00 XR70R
99 PW50
99 JR50
96,95 Sportsman 400
95 Xplorer 400
94 Indy XLT
87 Trail Boss
86,86,86,86,86 Scrambler
86 TRX70 x2
85 ATC350X
85,84 ATC250R
85 Red Tecate
85 LT50 x2
84 XR500R
84,84,84,84,83,82,80,79 ATC70
82,79 XL500R
83 ALT50
79,78,77,77,76 XT/TT500
76,75,74 XL70
72,71,71,71 SL70
72 Harley FX
72,71,70,70,70,70,70 CT70H
72 SL100
70,69 Z50