I have played the s/p. I found it to be alot more kick azz than given credit for.
-priest immune
-auto buffs
-auto heals
-fast snipe
-aggro lead
I also played the s/d solo just to help level my scout side. It does quite well. I have not tried it in party though.
-extra crit
-stun
-auto mana(rage/energy/focus) regen
-extra auto defensive buffs
-cleanse and antidote
Both were geared as scout.
Neither will show as "top" of the dps meter compared to other classes that are strickly individual dps, for instance the r/s and s/r.
i believe i can fill in some of the s/d info...
the auto-defense buffs and aggro buffs are one of those things that you never really notice when you have them, but then find yourself severely lacking when you don't (i went s/r vs. s/d)
the mana regen is ok, but kind of obsolete for parties at high lvls, but it does fill up your own mana, allowing you to pop elven eye almost indefinitely in a boss fight, the rage/focus/energy looks like it would come in very handy(too nub to have gotten 60 elite yet)
the stun is a great CC skill, and i usually pop on healer, then kill the other mobs, then kill healer, if no mage or other CC class in party, this comes in very handy
the extra crit is nice, but not as good as combat master

can some1 verify?), mostly because it doesn't modify crit damage
cleanse/antidote/unrooter are great when you need them, but this would be rare...unfortunately not too many instances/bosses use debuff's that can be removed with them, should broaden the range of debuff's that these effect
again, will never be top of scrut, unless u tanking for a instance 1/2 ur lvl, but in small groups, this combo is kick-butt