Difficulty Slider Preference: + or x ?
Depends I was doiung -1 x8 before shard drops became important to me now I hover from +0 x4 to x6
	It depends on the character.  BS/Regen, Grav/Storm, likely +.  WM/SD, Plant/Thorn, Fire/Fire, Ill/TA, probably x.  
Those I'm actively leveling:
Lvl 26 WS.  Actually leveling at -1x0 right now.  I was tiring of finding +1 groups that had Voids/Qs in them (or for some newer content, ambushes), or having a +1 Death Shaman summon +2 Dry Husks.  I am starting to feel like I am turning the corner on upping mob size to feed off of.  Bosses off.
Lvl 38 AR/Dev.  On base.  I went to bosses but came back after encountering Shock Treatment (ambush) and rezzing Freak Tanks.  Not having them seems a little easy at times, but having them is a little tedious with having to lay mines, etc.  Dunno where I'm heading with this one.
Lvl 31 Elec/Sonic.  Also on base settings, but with the confuse and the area sleep, I know I can handle larger spawns, which also benefits Conductive Aura.  I have bosses off, but playing him earlier today did feel like facing scaled-down Lts was kind of pathetic.  I think I'll go x2 and bosses at least when I get my gremlins.
Overall though, I don't see a need to press difficulty sub-50 like I used to.  More mobs on the way to 50 = more drops, so no real need to up +.  Fewer mobs per mission = more tips and arcs, so no real need to up x.
        
Suggestions:
Super Packs Done Right
Influence Sink: IO Level Mod/Recrafting
Random Merit Rolls: Scale cost by Toon Level
My general preference: Default settings. I don't optimize my characters or use much in the way of IO sets (no rare sets at all), and I don't use Incarnate stuff at all. Plus I like my characters to actually feel super, in that they can crush minions quickly.
A few of my weaker characters in the mid levels (such as my Kheldians) are set at -1 difficulty.