Just because the Devil has been portrayed as a "smoothie" in the past doesn't necessarily mean that he has to be portrayed as such in YOUR script.
Indeed. If I'm not mistaken, the Devil has also been portrayed as an incredibly smart but deliberately offensive blue-collar type, swilling cheap beer, belching, farting, being lewd, crude, and incredibly offensive.
Say, wasn't that Nicholson in The Witches of Eastwick?If you do what you want to, then my major advice is this:
GO BIG, OR GO HOME.
Nobody remembers the quiet successes; the operatic failures, they never forget.
Al B.