I think the key here is if the there is sufficient site supervision, if not then there could be problems which may be difficult to put right properly. (See
http://charles-church.org.uk/read.php?3,22,22#msg-22 as one choice example, other builders will have their own).
You will pay a premium for a Charles Church property over a Persimmon one, with a higher quality of internal fixtures and fittings.
I agree with what Tony said, talk to any existing owners.