Actually it doesn't quite work that way. The current rating in amperes relates to what the power supply is capable of supplying, and charging the battery almost certainly doesn't draw 2.5 amps. As long as the charging circuit draws less than 1.3A (and I would be pretty sure of this) then there will be no noticeable difference between charging with either the EE brick or the 1.3A adapter in the post. My empirical experience with using the PE adapter (which is rated at 1.0A) to charge my full sized EE is that charging time is no different than with the brick supplied with the EE. Admittedly I don't have quantitative data (charging times or amps drawn) to back up this statement.

The best thing about this thread is that to my knowledge, this is the only commercially available third party tip we know about that fits the Entourage devices.