as a first hand comparison my buddies have a CRF450 and a YZF 450 and from riding these two factory bikes i can say that the YZF will out torque and out top end the CRF all day long
as for the honda 50s i have 2 a 74 and an 83 50Z looks like a little elsinore i also have a 74 atc 70 3 wheeler a 69 and 70 CT TRAIL 70, A 75 XR 75, A 79 XL80, A 1969 YAMAHA ENDURO GT 80, A 1979 YAMAHA YZ 80, AN O1 HONDA CRF 50, and finally an 83 KTM 495. My brothers and I started collecting bikes for my dad (he said it reminds him of when we were younger) recently we've had and sold a 79 Honda CR250r Elsinore(red rooster), 2 75 Penton/SACHS(KTM)125s 1was a 6day trials bike and the other was an MX,AN 85 ATC 350X AND A 250R, A 75 HONDA ELSINORE MR125. We definately have had our fair share of the mini bikes