no not at all I'd rather change than have crasy loading times because it's over compressed....
and for a racing game it will be probably split into solo and multi or arcade and career etc.... 30 sec when I decide to change of game type for a same game is not really different than if I was switching between the CD of the NOD and the GDI for command and conquer back in the days... it was CD back then now DVD... I don't see where is the problem... don't worry one day in the future you'll have to change BR in the middle even if you have multi layers and side...
@ reask
do you drive ??? because saying PGR 4 and forza are the same.... is like saying waffles are the same as pancakes because you use the same ingredients.... forza is a simulation they try to recreate the reaction the actual car you are driving will have if you were actually racing it with the tunning you did yourself... PGR is an arcade racing..... they don't aspire to recreate the real feel you would have with the car if you are actually driving it.....
