I didn't read the whole thing but another thing you have to consider is the 450 is really choked to meet much stricter noise and emission requirements than 20 years ago. A stock 450 has an intake track the size of a quarter and a 118 main jet if I remember correctly. Just pulling the air box lid will require a 185 main jet, its a totally different bike after that.
I bought a 450R new and currently have an ATC250R. My conclusion is in a drag, with pipes and jetting on both bikes (also a cam on the 450, reeds in the 250 with more compression and 36mm flat slide) is in a straight up drag the 450 will win but on the 250 from 2nd through 5th it will pull slightly on the 450 but the 450 will jump it out of the whole and take it top end.
But one thing 4-strokes are generally known for are reliability and longevity. The 450 Hondas have neither. In my opinion a 2 stroke will greatly out last a 450 Honda. The power on the 450 is amazing but they are ticking time bombs. My brother had changed like 10 crankshafts in 450 Hondas.
08 Outlaw 525s
07 CRF70
04 Harley FLHRCI
04 TRX90
03 XR650R
03 400EX- XR650R engine
02 XR100R
01 Banshee
00 XR50R
00 XR70R
99 PW50
99 JR50
96,95 Sportsman 400
95 Xplorer 400
94 Indy XLT
87 Trail Boss
86,86,86,86,86 Scrambler
86 TRX70 x2
85 ATC350X
85,84 ATC250R
85 Red Tecate
85 LT50 x2
84 XR500R
84,84,84,84,83,82,80,79 ATC70
82,79 XL500R
83 ALT50
79,78,77,77,76 XT/TT500
76,75,74 XL70
72,71,71,71 SL70
72 Harley FX
72,71,70,70,70,70,70 CT70H
72 SL100
70,69 Z50