I would want to know why the rest of the owners are thinking of selling. Is it opportunistic or are there problems that they have been keeping quiet (until your vendor has sold) that they can’t afford to fix?
The tax issue is a trade-off and you should get advice on that. But I would be asking your conveyancer for a forensic study of the strata minutes before getting the chequebook out. And talk to the other owners if you can – they might know why the vendor is selling at such an odd time.