I have recently bought a 6910 and am very pleased with it.
I am using a De Longhi KG 100 grinder and am seriously looking at upgrading it. I have done a few tweaks to get "espresso" quality grinding, but as others have commented, the grind is not consistent. Well that may be due to humidity lately, but I am consulting the bank manager about what I can afford for my next grinder. I was considering a Sunbeam EM0480, but there seem to be a lot of issues, and currently the Iberital Challenge or the Isomac Professionale look to be the next price point. I would be interested to hear comments by users of these.