I think that you should be fine with what you're planning to do. I did the same thing awhile back and it's been very rewarding so far.
While a reef tank requires a substantial investment, the planted tank can be set up with less expense (especially with the equipment that you already have). As for maintenance, I'd have to say they're pretty close. In a reef tank, once things have settled and you're in the rhythm of things, it's pretty easy. Everything becomes automated to a degree (calcium reactor, lighting, dosing), and you just have to deal with the usual maintenance (removing coralline from the glass/acrylic, moving corals around, water changes, fragging, etc.).
In a planted tank, you have to deal with similar issues with regards to maintenance (removing algae from the glass/acrylic, water changes, pruning, redoing the aquascape occasionally). It's automated to a degree also, with CO2 setup, lighting, dosing (autodoser, which I'm sure you're familiar with).