There will always be a 'better' device coming. If you wait for that, you'll never buy anything. Buyer's remorse of buying a device and then discovering a new model next week (because we all the want the newest, shiniest model - even if we have no idea how that will make our lives better) is always out there.
That said, the current crop of iMacs and MacBooks are running the first generation of M processors, so if anything is going to go wrong with this new system, this is the era it most likely will. But if you've not seen any reports that have frightened you off - and there's been no reports of mass failures / spontaneous combustion that I've seen - then why not get it, especially if you luck into some sort of a sale?
Speaking of which, always check out your country's Apple Store website 'Refurbished and Clearance' for discounted models - Refurb'd units here (could be returns via buyer remorse / wrong model / open box or minor work needed) are individually checked out (so arguably better than factory floor new), cleaned and repaired, if needed. Comes with full Apple warranty and AppleCare+ availability. Stock changes all the time.
Sidebar: While I appreciate there is this contingent that always seek to 'super-size' everything (see America's love of pickup trucks, Hummers and SUVs when really, most everyone probably just needs a two door), I really am sorry people are flogging for even larger screen size on iMac (I daresay it suggests our eyesight is getting worse - looking at screens all day) and would have liked to see a 21" maintained with a M processor. Something that doesn't necessarily take over space in a home office.