For a few effects, above 127 is not negative. I cannot remember which ones, however, though I believe 255 works for 21 and 22.
Oh, and I improved on this one Code: /summon Skeleton -161.40 5 -708.43 {Equipment:[{id:261},{id:301,tag:{display:{color:3361970}}},{id:300,tag:{display:{color:3361970}}},{id:299,tag:{display:{color:3361970}}},{id:298}],CustomNameVisible:1,CustomName:"Merliz",Riding:{id:Bat}} I can't make the leather hat blue as that would take me over the character limit of command blocks
Imagine if EMC would use such coding for mobs with custom clothing, with enchantments, damage reduction/resistance, difference in sizes... so many possibilities... It all looks very promising to me!
Oh, Aikar already does The example you quoted there is actually similar to our own Marlix. Marlix itself wears all the special armour and weapons that you can get as drops. It rides around on an invisible bat with resistance IV to make it invincible.