Central Air Install

I will be upfront and admit that I don't know much about Central Air. I have a HVAC guy wanting to put in the following system in my house
2 5 Ton systems with ADP BCRMC6460S3N4 air handlers with Fedders 13 Seer 5 ton condensors. He tells me that the Air handler is a 10 SEER unit but has a expansion valve built into it that makes it 13 SEER. Is
this true? He tells me that this Air Handler is better than the First Company air handlers others are proposing. Is that true? He also tells me that Fedders uses Copeland compressors and therefore it is very similar to the high priced brands. All the listings I have seen on this forum state otherwise. What is the opinion of this forum with regards to Fedders?
He also wants to put in a single return each on the first and second floor. The other opinions I have gotten say that I need to get multiple returns on both floors for efficiency. He tells me that the it is a nightmare to balance the system with multiple returns and he won't do it, no matter what. What is the truth here with respect to single return vs. multiple?
Please help as I need to make a decision soon.
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