Denis McShane was found guilty in court of fraud - he had knowingly and deliberately set out to defraud the taxpayer by submitting false invoices. This is a far bigger crime than Ms. Millers.
Ms. Miller is guilty of gaming the system as it then was. Many of her colleagues, across the political divide ( 389 of them, to be precise) have been found guilty of exactly the same offence as Ms. Miller, to a greater or lesser degree.
Many commentators have pointed out, quite rightly, that had such "misunderstandings and mistakes" been found in someones company expenses clam, they very likely would be facing gross misconduct and summary dismissal charges.
I would strongly support the introduction of a "right of recall" law, proposed by people like Zac Goldsmith MP and Guido Fawkes, the political commentator. And to make the assessment of expenses and repayment schedules entirely independent of MPs.