The problem with Maroon is the question of whether he's the right winger for Malkin and Hornqvist. I'd only want to add a winger like Kane, I wouldn't want to add a lesser depth winger. I just don't view it as a need.
IDK... I really really like the idea of adding a grittier LW. I get that it's more of a want then a real need... but someone like Smith or Maroon (particularly Smith) who can play a top 9 role either with Malkin or on the 3rd line with Kessel or whomever and give us something different then what we already have is appealing. We have a LOT of smaller guys who are fast and skilled (or semi skilled). The only player we have who plays a gritty game is Hornqvist and Reaves/Kuhnhackl. And the latter two are both guys everyone wants out of the lineup. I have no issues wanting better players then the latter two on the 4th line come PO time... anytime really, but especially for the POs. But we have certain needs that those two fullfill (grit/physicality and PKing). Rust can handle the latter of the two, which can bump Kuhnhackl. But if we bump Reaves for anyone of the names that usually get tossed around here... that's leaving us with Hornqvist as the only 'grit' in the entire forward group. I get wanting speed and skill... but there needs to be some sort of balance.
Maroon would be cheap and would be a rental, and would cost accordingly. Smith (unless moved as a complete cap dump - unlikely) would be a little more expensive and has term (something that needs to be factored in a little as to fit long term). But he also has the ability to be a quality center for PKing and for injuries to our other centers.
Either of these two guys (or others - McGinn, Martinook, Weise, Grigs - although those latter 3 are certainly at the lower end of the scale) would give you a lot of different options for your forward group. You want someone gritty with Malkin? No problem. We're all liking the Hagelin/Hornqvist pairing with Malkin. But what happens if come PO time we need someone else to fit with Crosby? We had issues with this last year vs CBJ until Hornqvist was moved to the line. Another player with some grit who can play in the top 9 would give us a LOT of options. It might not be possible (cap/cost), but if it is, I really want that.