Tell ya what ... personally I look at a reef tank as just a saltwater tank with a ton of live rock, a deep 3-4 inch aragonite sand bed, a good protein skimmer, decent lighting, and corals / fish. That's it !
I would not fear it at all ... matter of fact the fewer fish, the less load on your filtration system. You don't have to go FULL BLOWN reef right away either.
Say you tried this;
Set up your tank initially with deep sand bed and 20 to 30 pounds live rock. Let it cycle with a couple raw shrimp. After a month or so you will be anxious to add some critters - that's cool .... add a good clean-up crew. Wait another few weeks and maybe add 1 fish. Wait some more.
Depending on your budget, you will want to get good lighting if you want corals, but you don't need to go all out right away.
The key is having patience and not overstocking it with fish. Hard to do but a MUST in reef/salt tanks.
Go easy, plan your tank from the beginning.
What do you want to end up with, how much time and money are you willing to spend, etc.
Converting from a FO to a FOWLR or to a full reef tank can be done. But I would suggest if anything ... go with deep sand bed from the start.
Aragonite sand is best in my opinion.
A Whisper or other power filter would be okay if you want to add some circulation aside from the powerheads, and good way to run carbon too.
Fear not the reef tank ... if you want to do it ... get a couple of books first, and read up on what you are getting into first
Brian