Be careful what you wish for. If the SH2ac is causing problems, definitely get it swapped.
But if you just want a new shiney hub, be aware that it seems VM may have exhausted new stock of the Hub 3, so you could get a secondhand one that's nearly as old as your SH2ac, and just had a quick wipe to remove the baked bean stains. They might send you the latest and greatest Hub 4, brand new. But if you do a search in these forums it seems some people are seeing significant teething problems. And as a guide, the teething problems of the Hub 3 lasted about two years from launch, and VM refused to say anything about progress with the fixes.
And the wifi of both Hub 3 and 4 is not materially better than the SH2ac. VM had the chance to include the latest wireless standard (wifi 6/802.11ax) for the Hub 4 but chose instead that they'd rather the development budget was spent getting the VM brand on the box.
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