I'm a constituent of John Bercow and signed his nomination paper at the last election (although more than one was prepared and I'm not which one was used).
I want MP's to be paid sufficiently to be able to do their jobs properly. Ann Widdecombe was right when she said that low salaries will mean that MP's will be restricted to the wealthy which is not a democratic approach. Unfortunately we insist of paying MP's relatively low incomes, especially when compared to the Continent, but expect them to still do the job correctly.
I therefore feel the expenses affair comes down to personal integrity. Claims may have been "within the rules" but MP's were allowed to claim without receipts and to switch nominated properties because they were trusted not to abuse the system.
There will always be some who take advantage of any system. The Kirkbride/Mackay claims are so outrageous I believe they should both stand down but if the only doubtful claim that John Bercow made was to flip properties once, it doesn't show a pattern of behaviour that deserves to penalised by being forced to stand down.