Gryphon Antileon vs Antileon Signature

Hello,
I would like to know if the new Signature version of the Antileon is really better (sound quality) thant the previous one. How are there comparing ?
It's easy to find an used Antileon for a fair price, but Signature ones are a lot more expensive (because they are newer).
And do those amplifiers have a good fiability ? A 7 or 8 years old amp is a good choice or the risk of technical problem is very high (I know they are gettong very hot, so it stresses the electronics components a lot) ?
Thanks for your advices.