mono block or bi-amps which would you pick?

Assuming the speaker specs are accurate, which can often be a big "if," and assuming about 3 db of "room gain," it can be calculated that 28 watts into each of the two speakers will produce an SPL of about 106 db for a centered listener sitting 10 feet from the speakers. 60 watts would produce about 3 db more than that.

Either number is more than enough volume for most listeners on most recordings. Exceptions are likeliest to occur on material having extremely wide dynamic range (i.e., a particularly wide difference in volume between the highest volume and lowest volume notes on the recording, such as some large scale classical symphonic recordings that have been well engineered with minimal or no dynamic compression), or if you routinely listen at the levels that are often encountered at live rock concerts.

Regards,
-- Al

Al... thanks for the inside tips.   Really appreciated! 

If money is no object then have a custom designer make you a pair of amps.  Something like point-to-point wiring, custom transformer, copper chassis, better resistors and capacitors, etc.

Mono blocks as custom designs would be heavy.

Happy Listening.

There is no rule and no single answer to your question. It is all system dependent.  I run one system with 4 mono amps, biamping each speaker, and I run another with a stereo tube amp on it's own. 

I'd rather have a good sounding stereo amp than a pair of not as good sounding mono amps.

Wsphon... i totally agree with your point!