I found GP's to be soft....
Before I "graduated" to Li-Po, I used GP's for years. My first and only IB pack was a IB3800 and it had PUNCH that surpassed the GP's to the point where I thought the GP's were soft. If they are looking to give you IB's instead of GP's, check the cost difference, and see if you can be compensated with additional cells. If the IB's are less expensive, take the IB's and run!