It's extremely unlikely that the bit rates will ever go up on DAB. The BBC say they would like to provide higher bit rates, but the commercial radio groups will simply block them from doing so, and the commercial radio groups have absolutely no intention of increasing their bit rates.
The bit rates of all the BBC stations are higher on Freeview, satellite and cable than on DAB apart from Radio 3, and even Radio 3's bit rate is reduced whenever Radio 5 Sports Extra is on-air in the daytime.
There's also the issue that BBC7 is mono on DAB but stereo on Freeview, satellite and cable, and Radio 4 is reduced to mono on DAB in the evening if Radio 5 Sports Extra is on-air.
So, yeah, if you're not interested in the digital-only stations then definitely stick with FM, because it does sound far better than DAB. But if you want the BBC's digital-only stations or some of the commercial radio stations then satellite is the best, followed by Freeview then cable.
In the next, say, 1-4 years, if the BBC gets its act together, then we should get live streaming radio that's got a higher audio quality than anything that's currently available, even better than FM. Have a read of this to give you an idea of where we're headed:
http://support.bbc.co.uk/multicast/why.html
http://www.bbc.co.uk/broadband/info/multicast.shtml
Basically, internet bandwidth for live streaming will no longer be a problem once all ISPs support multicasting, so they should provide very high bit rate streams with modern audio codecs, so the audio quality will be CD-quality.