jriv
I agree that your technique would work, and have indeed used it myself!
I was just pointing out an alternative method.
I remember trying to make a night curfew at TXL, and gettting direct to the OM from near the UK east coast. As I recall the A320 is very speed twitchy at M0.80 and above (Mmo 0.82), so we did use both techniques (ALT + IAS hold) which worked well - the Ground Engineer had left the destination assuming that we would have to divert to SXF, but we touched down with about 3 seconds to spare! Well worth the extra fuel burn.