Really? Google "climb cut" RAS. The very first hit:
Who's ignerint now?
AND, btw, this explains but another lie on the dualsaw mis-infomercial: You CAN cut in either direction with a circular saw (backwards would be climb), you just gotta be careful, and use a "stiff arm". Not recommended, of course.
And, indeed, the dual saw DOES facilitate this bi-directional cutting, but it is an utterly trivial feature. They also strongly imply that *because* of the opposite blade rotation, the dual saw can plunge cut and a circular saw can't. Carpenters plunge cut every day with circular saws. Sheeit, you can plunge cut with a recip saw, if you know what yer doin.
Well, *I* can plunge cut with recip saw..... clearly YOU can't.....
Btw, I disagree mightily with Contributor D:
Climb cuttung, as he correctly describes, indeed requires a "stiff arm", and is thusly a very big pita for thick material. Otoh, Push cutting (conventional) imo is MUCH preferred on an RAS, and safer. And *easier*.
Conventional cut is, of course, how one uses a table saw or circular saw.
Otoh, machinists generally prefer milling in climb, altho material and tooling can vary the equation -- strangely, I've had much better finishes in some mateials using conventional finish cuts... but, gee, look who I'm talking to.....
Any questions?
Oh, btw, I need not have even googled or cited anything, as the "physics" that yer ignerint buddee RicodJour refers to is self-evident, and I could have argued this from geometry alone. Too much work, tho, and no doubt futile for you and yer dualsaw buddee, so I did the google for you.. I'm sure the folks on rec.woodworking can help you out further, if you are still in your chronic daze.