I would say some Class D amps are ready for prime time but others are not. I'm still seeing Class D amps having problems driving a reactive load and keeping the frequency response flat. I really don't care about the efficiency or weight but am curious. The Buckeye amps look tempting but only to see for myself. I'd likely sell it after a couple of weeks though.
I have tried a number of "traditional" amps on difficult loads (my Gallo Nucleus Ref 3.2 speakers) - and Crown XLS class D...
The traditional amps mostly do not/did not double down on W as speaker impedance drops... in theory 1w @ 8ohm should= 2W @ 4ohm and 4W @ 2ohm.
Traditional class a / ab amps that can do that are rare / expensive.
Most class D amps can't do it either.
The XLS series from Crown do - and into a difficult speaker load - that does the magic.
Ultimately it is not whether it is class A or Class D (or anything else) - but how well it handles the speaker load.
With easy to drive 8ohm to 6ohm speakers.... you can probably use any amp and get decent results... you won't experience the same thing if your speakers drop below 2 ohm, and some exotics go as low as 0.5 ohm. (many amps go up in a puff of smoke at that point!)