... finally, any thoughts on this vs heir 5.0 (aside from the whole - 'amg no more wizard at heir thing')
Heir 5.0 is an excellent earphone, but is slightly more laid back than the Amps.
The Amps are easier to fit and seal, actually one of the easiest earphones to fit and seal that I have ever used. The Heirs are fairly easy to fit, but not quite as easy as the Amps.
Sonically the Amps have a great deep extension without much of a mid-bass bump that other earphones often have. The Amps have crisp highs, good mids, and sound great with whatever you throw at them. They seem to retain a fun sound while still capturing the complete sonic spectrum.
To my ears neither are sibliant.
To me, the Heirs are more laid back and lack that sense of excitement that I get from the Amps, the Heirs also have good bass extension but it seems to hit harder and quicker on the amps.
They both have good mids and highs, but again the Amps have slightly more life to them. They both have excellent detail as well.
To choose just one, I would keep the Amps over the Heirs but that would be tough to, as I do enjoy the Heirs for what they give.
I should add that I think that both earphones perform incredibly well at their related price points. They are both better that any $200-$400 earphones that I have heard, and may be very close or equal to $1000 earphones, but I have only heard the 1plus2 and that one is really the best earphone in my collection. The 1plus2 is a stay at home earphone, the the Heir's and Amps are both very portable.