There is a v. interesting review offered by the July issue of the Diver magazine.
The top scored regulator is not the most expensive model (ease of breathing, WOB), it does worth to take a look!!! There was an issue about this: is it possible that some of the local magazines are biased? When the Diver magazine came out, it did confirm that some brands are in fact v. good (same as the local magazine's comment) and the review added some insights about the performance of different regulators on the market. Also, the review confirmed some ideas given by some users here.
If you do not need to get a copy, just look it up at your nearest library. Diver magazine from UK.