TBH I would say that the warranty sounds good, if for example they will replace the light if diodes start to fail AND if the output diminishes beyond a certain percentage. I would want to clarify the terms of the warranty ya know?
2.3 umol/J sounds good, spectrum looks acceptable. 5x5 coverage with 860 watts sounds about right at 34.4 watts per sqft.
I don't know about the diodes personally either so you may wanna get other opinions for sure. Due diligence is required here, definitely on the warranty issue. Are they gonna pro rate you and make you basically buy a light if one shits a brick in 2 years? What will they do if it shits a brick in 4.5 years on the 5 year warranty and they don't even make / stock that model anymore?