I wouldn't. KG will likely go down as the better player, but Gasol fits our team better and is significantly younger.
I certainly wouldn't complain if this hypothetical trade went down, obviously, but for long-term and practical purposes, I'd rather have Gasol.
Sure, you can factor in age, but in terms of overall skill set, Garnett actually fits this team better, especially as Bynum develops his post game.
Also, Garnett would pretty much solve all our defensive woes that come whenever teams put in their small lineups, for Garnett can guard every single position with ALl NBA team defense.