I'd say skip the iPhone 4S speaker and get a Scale Sound Systems (
www.scalesoundsystems.com) speaker instead. They are well worth the extra money. If you only have space for an iPhone 4S speaker, get his Rapido GMD-1 speaker - it's made to replace the iPhone 4S speakers.
I know that KPack Kevin from RPUG has a speaker comparison video and it's an amazing difference. J.T. of SSS also has many comparison vids on his site as well.
Not affiliated in any way, just a
VERY satisfied customer!!!