[quote name='prmononoke']I don't know if the current one is the old one, but I love the look of it.[/quote]
It looks like it's trying to straddle the line between the look of a real guitar and plastic guitar, but failing horribly. The paint job just ruins it for me, while the RB2 guitar succeeds with that same sunburst style.
DLC is fully compatible with both RB games, Harmonix hasn't said anything different about that.