Well the new modem duly arrived - a Huawei device rebadged by Telstra, unlike my previous unlocked MF910V which was a rebadged ZTE unit.
Physically it's about the same size, but a bit heavier and bulkier, possibly due to a heavier battery being used to give it a longer life.
Fitting the SIM was a bit of a pain - it uses a mini sim and it needs to be slotted into a pretty stiff clip and locked into place, but then that's something you only have to do once.
One nice feature is that it can double as a pager and receive SMS messages - Telstra use this to send you messages about your data running low, or about planned service outages, but there's no reason why you can't use it as a pager substitute.
With my standard connectivity test - look at a UK university's home page - in this case the University of Huddersfield - performance was obviously slower than over our NBN connection but felt comaparable to the performance of our previous ADSL link.
The charger is a standard USB charger but one with the USB slot on the top, not the side meaning it doesn't take up two sockets space on a standard powerboard, which is a nice ergonomic touch.
All that remains to do now is to field test it - something that will have to wait a week or to. In the meantime there's the question as to what to do with my old unlocked device - whether to keep it as a spare or in case of overseas travel, or attempt to sell it ...