the advantages of using a saddle pack vs a stick pack on your pro2 are:
- you can use a battery tray to equalize your cells.
- if you get hit from the side, the stick pack might eject (happened to me on several occasions before i switched to saddle. also, my chassis got torn off where the stick pack holder was screwed on.)
- you car will handle slightly better because of better weight distribution.
- if you just file the battery slots and use strapping tape (though not very convenient), your car will have a lower center of gravity because the cells sit lower on the chassis.
the disadvantage would be if the saddle packs eject on their slots, they may short because the cells are close together when you mount them. it helps if you put electrical tape on one side of the cells to prevent this.