Any Sony 850 or 860 owners out there?

Anyone out there got one of the big Sony multi-changers?

I'm looking at investing in one of these machines and was wondering if any owners out there can help me with a couple of questions....

1- Can either of these machines swap disc sides? (mainly a question for the 860 I think)

2- Is there any difference in performance between the two?

3- Are the menu problems that bad and does the 860 correct them?

I'm wondering whether the 860 is really worth roughly an extra £150 (best prices I've found are about £380 and £530). Ok it's smaller but I doubt I'd need another 100 disc capacity...

If anyone could help with these questions it'd be a great help to all but my bank manager!