Some games are simply not compatible with the swap method. We could get alot further into detail on the pros and cons of the ole swaparoo but its all been covered plenty of times already so I wont rehash it all. Its all cons and no pros anyway. If you want, you can check out some of the related threads listed at the bottom of this thread and do a search on swap magic.
I just try to keep it simple and to the point. Swap Magic sux! It will wear out your drive in no time. Swap is also much harder on your laser as it has to read from all of the swaps to finally play the game.
S.W.A.P. = ( Still Worthless And Proven)
A real chip will directly boot your game backups and doesnt have any compatiblity issues to worry about. Every game backup I have thrown at my Duo chip has been flawless. I have had a few bad burns however due to damaged media but for the most part, no probs here.
Normally rather than get into a bunch of details, I just recommend what works and thats it. Straight and to the point.

Call me "simple" I guess.