Personally, I'd be happy for another Hyman-type out of Johnsson. As for Kaps, he's sure shown some great solo offensive work. I'm not sold we've seen him do anything with others. At least yet. Someone stated he played with Plekanec. Plekanec had the 3rd highest points/60 in the playoffs for the Leafs. I can't see blaming someone who's put up 600 points in the NHL as a huge excuse for your play-making abilities. Now perhaps Kaps could produce more goals on a higher line, but if his game restricts what types of plays you'll see from his line, they'll be a lot easier to be shut down. Kapanen put up 53 assists in 115 games for the Marlies. Johnsson just put up 14 assists in 16 games in the AHL playoffs.
In the last 10 years, out of the 1481 NHL players that have put in at least 50 games in that time-frame, Kapanen is 1478th in assists.
In the entire history of the Leafs, Kaps is 458th out of 459 players for assist by players who put in at least 50 games. Tied with greats like Keith Aulie and Frazer McLaren.
Think Kapanen is just fine doing what he's doing, there's better options for the top 3 lines.