Personally, I think SF:1 mecha are all easily overlooked because there are more SF:2 mecha than there are SF:1... and SF:2 being more fleshed out as they are the main war machines of the game.
For me, SF:1 mecha was never a viable combat platform for a player because I think the game is balanced for SF:2. When I was playing GH1, they hardly posed any real threat.
Someday, when I find the time, I want to try and turn GH1 into mostly SF:1 with only a few mechas as SF:2