A top class novice can run in any race from 2m to 3m, its much of a muchness. You might bump into a top class 2 mile specialist in the Arkle or Supreme but most years you wont, and same goes for the Bartlett and Broadway, you might bump into a top class stayer but you probably wont.
Jango Baie ran in the Arkle because the Golden Miller became a handicap, wouldnt read much into it. Hes obviously a stayer as even two and half on good ground is sharp enough for him.
All of these good jumpers are basically just high class plodders, theres a bigger difference between 5f and 8f than there is between 2m and 3m. Always laugh when theres a question if some 2m novice chase winner will "stay" 2m4, of course they will.
You get the odd Harchibald or Go Native who want 14-16f but Solwhit, Hurricane Fly, Kauto Star etc is the norm for a top class jumper, 2 miles, 3 miles, its all the same. The horses that run in the 20-21f divisions are usually there because theyre not good enough for the Champion Hurdle or Gold Cup, theres definitely a lack of speed but rarely a lack of stamina.