Here is my full time line for my Priority Settlement Visa through LA:
Biometrics: September 2, 2010
Sent out app overnight mail: September 2, 2010
US Post Office gives receipt of package: September 3, 2010
Labor Day postpones processing one working day
UK Border Agency sends processing email: September 10, 2010
Approval from LA UK Border Agency: September 15, 2010
Received Visa via UPS: September 16, 2010
Total processing time from initial physical receipt of visa application: 8 working days (including the day it was received)
Landed in the UK: September 23, 2010
The priority service is definitely the way to go. Good luck!