I’ve ridden both, I used to own a Smuggler and regret selling it. It’s a very capable bike, sometimes in the big stuff you can feel the limit of the 115mm out back but that’s not too often. It was really quite playful too, a fun bike to make the most of small trail features. At 5’8″ I owned a medium but would have liked to try a large out as I prefer a longer reach, if a large frame came up 2nd hand i’d buy it.
The mega is a much bigger bike it needs a bit more muscle to get it moving around but it is quick and felt very smooth, possibly too much for some riding but I admit I liked it. Similar to smuggler you can size up if needed.