ark,
thank you so much for all your precious information.
From you reply I understand,
I140 and I485 concurrent filing == max time of any one of the process i.e 4-6 months

if i do premium for i140 and go for concurrent filing of i140 and 1485 == still max time of any one of the filing process i.e 4-6 months

so, no need to go for premium process with i140 if one is planing for concurrent filing of i140 and 1485 as the time process would be same in both cases.

correct me If i understood incorrectly.

Thank you once again.