I wouldn't say more consistent, he's just way lighter and climbs way better. Wellens is probably a better rouleur and also better for flemish races (I never understood why he focussed on the Ardennes for so long).Lennert much more consistent. Not sure about three weeks, but he'll definitely be a player in your average Paris - Nice.
If he ever will be a GT rider is obviously too early to tell, but after De Lie he's a 2nd gift from God for Lotto.