In the same boat. I was going to get both, but I got the demo and it really makes my hand cramp up, not to mention that I lost a lot of hype when the final roster was revealed and none of my wanted newcomers got in, and they cut some of the characters I like. Personally, the only thing that the 3DS has going for it is portability right now - since Nintendo really wants to make the same game twice, I don't see the point in getting it twice. Now if they actually did make it as two games, I probably would get both, but as of now, we're getting SSB43DS and SSB43DS-in-HD. Still not a fan of that, considering that Ice climbers and Pokemon Trainer were cut because of the 3DS limitations, and that's been confirmed.
However, if this Tower of Smash leak ends up being true and we need to hook them together to get Mewtwo and Ridley, I will download the 3DS version that second.