I have just moved from Lenny to Squeeze. I did it the cowards way by shifting from one VPS to another, taking up Bitfolk's 2 weeks offer. It all went extremely well except for one problem that I have just solved after hours searching logs, uninstalling and reinstalling etc. Thought I ought to post it here in case anyone else hits the same problem. (When I have done my other VPS I'll add this to the Wiki)

I found that I could not get rndc to work. This led to very intermittent failure to allow transfers to slave servers. I had all the correct permissions and keys and everything in the right place. I had iptables set up to allow input on lo and from 127.0.0.1. In the end, I had to set up an explicit rule in iptables to allow input from 127.0.0.1 to 127.0.0.1 port 953. Never saw this on lenny nor on an "offsite" squeeze machine. I can't understand why this time it needed that one explicit rule. Anyway, all's well that ends well and it is now all working perfectly