Yeah I usually use deadline for mysql intensive servers but on regular hosting servers Ive always used AS and just recently went to CFQ.
So last night I switched to deadline for 2 servers running litespeed. cp is the one I had most of teh problems I mentioned above because it is a fairly busy server. Cp2, there isnt enough clients on yet so has been no problems.
Anyway running with deadline I go in and rm a huge directory of old backups and ran uipdatedb at the same time, for the lifge of me though I could only get the load to like 5.
As far as litespeed ran I think I saw an improvment. But starting at 4.5 and up some page loads would stall for about 3 seconds BUT was few and far between and very well could have been my connection but I did see an imporvment.
I think its pretty safe to say litespeed will run better with deadline as default I/O scheduler then again I just have regular SATA hds. I still got lots of more stress testing to do and plenty of real time attacks and high usage to deal with so I will know for sure within a week or two.