There may be some benefit in charge time for boost charges going from the stock 750mAh charger to something such as you suggest, but your battery will suffer a shortened life in the process. In fact, Motorola went from a 780mAh charger on the OG Droid and Droid 2, to the lower current of the ones that shipped with the Droid RAZR and RAZR MAXX for that very reason. Slower charging rates (lower current) will extend the life of the battery (number of charge cycles before it will only hold 80% of what it was originally rated for).
Also, it's been proven that with Lithium Ion batteries although charging faster will get you to about 80% charge in a shorter time, the other 20% will take longer and the net result is very little if any time saved. If you must charge faster I don't believe you will see any benefit above 1,000 mAh, because the phone's charging system has a current limiter built in to prevent overcharging and excessive current during charge. It may be that the total maximum current rate allowed is less than 1,000mAh, but I am nearly positive it is no more.
Here's an interesting fact...my Motorola Navigation Dock came with its own Motorola Car Accessory Adapter/Charger, and it's called a "Rapid Charger", and yet, it's rated at 750mAh (same as the wall adapter). What does that tell you?