I'm using T1004X with the G20 ballhead.. I find that reverse fold is Ok... Just that need to adjust the position of the ballhead abit when reverse.
But i'm loving it... Yeah..
Have seen a G10 hold a D3 + 24-70/2.8 steady, so it's not entirely useless... but if functionality is not compromised, and the cost difference is small, probably feels more secure to get G20 over G10...
I am using A550 with B-1. Like the B-1 ballhead. Very smooth handling. I did not know about Sirui when I bought my tripod but no regret buying Benro. Maybe can try buying Sirui CF tripod for my upgrade since the price so competitive.
Im using Benro A650-EX with BH-2 ballhead. Super solid feel and rated 8kg to support my D90+Sigma BigmOS lens. I havent used Sirui so no comment on that. Check out this pic I found on the net: