I just wanted to report back... I ended up purchasing the RS-2E and the RO150. They are both amazing sanders and I'm happy that I got them both.
The RO150 is simply amazing and aggressive- yet easy to control. I was worried because I had heard so many reviews saying that it was hard to control - I'm able to just let it move on its own with the hard pad and in rotex mode. With the soft pad I have to pay attention and concentrate on keeping it flat. All in all, I'm thrilled with it.
The RS-2E is great for the final sanding pass with 180-220 grit. I tried using it with 60 grit to level out a couple of glue ups but it was just too slow for me. The RO150 is definitely better for that but I'm much happier using the RS-2E if I'm sanding all day. It doesn't give me any fatigue.
Thanks for everyone's input and feedback. I echo all of your thoughts and I can't believe I waited so long to get a Festool sander. I think an RO90 in addition to what I purchased would really complete my kit!