I recently moved from NewNet (Home M - 12Gb) to PlusNet Pro. My exchange is 21CN. With NewNet I used to have a rock-solid connection with a sync of 6000 - 6400. IP Profile of 5Mb to 5.5Mb. Very steady speeds, so all very good. The only trouble was I started exceeding 12Gb a month towards the end of last year, so had to look for other options (didn't want to spend more than £18 a month!). PlusNet Pro offered me 20Gb at £16.49 a month (Market 3).
I joined at the end of Jan when they introduced their "3 months free" offer, that all worked flawlessly, as did the 50p monthly credit to the person who recommended me.
Speeds for the first 4 weeks on Pro were a little variable while things settled in (IP profile dipped to 4Mb at one point), but it all came good towards the end of Feb and I'm now at a 5.5Mb profile and holding steady (as with NewNet).
Diagnostics and information in the members area far better than NewNet. Never had to call NewNet support, not had to call PlusNet support either, so can't compare either - the service just works - which is all I ask!
(That reminds me, must change my sig!)
NEWNET - ADSL Home 8050 M