Reskinning is useful for all sorts of things (so you're wrong there), yet none of those things include changing the level of an antagonist by +10 (so your original example remains wrong).
Sure, explain it slowly for me again, if you must.
You didn't actually post any builds. Show me the stats, feats, powers, and synergistic equipment.
Or don't. I'm fine if you walk away and "consider... your... self... victorious..."
Cheers, -- N
1. Lol, you still don´t get it...
Orc --> Drow No level difference, as you can level up and level down as you like
Problem: What do players expect when they see the enemy?
An Orc which is powerful melee combatant that relies on a charge, drow: darkness or fearyfire...
2. I don´t have to show you a specific build as it is obvious that daggermaster is not the best choice, if you wield a rapier and if have greater strength than dexterity and thus can make good use of at will twin strike...
... also i don´t have to put items into any build, as I don´t consider (magical) items core to a build...
edit: and the 18/12/16/8/14/10 line are stats... and brawny rogue is a build... maybe you need to read more careful...
so that you needn´t read older post again:
e.g.: a longtooth brawny rogue with a rapier, paragon multiclass as ranger is arguably better than a longtooth shifter brawny rogue wih rapier taking daggermaster as paragon path...
edit: if you allow for dragon magazine, a scimitar dancing duelist brawny rogue also looks quite workable...
stats: 18/12/16/10/14/8 after racial