Trade/sell his old 3DS for the New 3DS and get a better gaming experience. Smash 3DS on the old 3DS isn't bad but not necessarily ideal with those long loading times.
Nintendo should have made Smash an exclusive for the New 3DS.
Yeah fair, if OP sells his 3DS, then buying a new 3DS makes sense.
I'd rather get a PS Vita, PSP and DS lite for the same price (or less?) than a new 3DS though.