vbulletin 3.8 easy to manage easy to modifiying, and many plugins competible

i think can't downgrade vb 4.x.x to 3.8.x coz this use diffrent script

vb 3.8 use normal script vb 4 use script like <vb:....> when u downgrade then this will wil crash

vb 4.x.x use colocation table is diffrent vb. 3.8.x use latin1_swedish_ci and vb 4 use utf8