There wasn't much that Reason could do, which Live 7 couldn't do but now Live 8 is out and it's just as well equipped to make beats as anything else. I make beats that I sell to local amateur artists, some completely original tunes (including beats synths and sampled instruments) to use for remixes, as well as mashups and about everything else and I do it all in Ableton. Ableton is perfectly suited for producing music of any sort, especially beats.
The drum rack is awesome because you can load 127 different samples into a single rack and then inside of each of the 127 slots you can stack different samples on top of each other, add all the FX, etc. Lots more room for creativity. And plus, like I said, Ableton 8 only made everything better. It's new sound engine is in par with all the top DAW's for sound quality now.
Plus, Reason is pretty much only useful to make your own beats and tunes and stuff, but Ableton is suitable for that too as well as remixing or a whole list of other stuff. So it's also more future-proof because you may take up an interest in something else musical too.