To use or not to use
It is advised to use hardware acceleration only if you have complex custom computations for scaling, rotating and translating of images, but do not use it for drawing lines or curves (and other trivial operations) (source).
If you plan on having common transitions and also given that you have already considered scaling, recycling, caching etc, than it may not make sense to burden your project anymore. Also, any efforts spent reworking your code to support hardware acceleration will not effect users on versions below 3.0, which are ~36% of the market as of May 8, 2013.
Memory
Regarding memory usage (according to this article), by including Android Hardware the application loads up the OpenGL drivers for each process, takes memory usage of roughly 2MB, and boosts it to 8MB.
Other issues
Apart from API versions, I presume it will also affect battery life. Unfortunately there aren’t any benchmarks on different use cases online in order to draw a line on this one. Some argue that in given cases because of multiple gpu cores, using acceleration may save battery life. Overall, I think it would be safe that the effect won’t be too dramatic (or Google would have made this a major point).