The patch is actually different fro what you think, I believe. Here is a quick rundown. There are four main bootcodes. v1.00, v1.01, v1.02, v1.03. The first three were simple upgrades. These make sure you are running a valid OS using whatever security measures (I believe a 512-bit RSA). v1.03, however, is found in newer models and makes it so that you cannot downgrade your OS (in other words, going from 2.55 down to 2.43 or 2.53). The patch merely allows you to downgrade your OS and it bypasses the security check of the new 2048-bit RSA being used (saving a lot of time when you load a new OS).
Anyways, the only real difference between the OSes seems to be that 2.55 includes Stat Wizard and other tools and it uses an extra sector of Flash compared to all the previous OSes (one sector=4 flash pages = 65536 bytes). 2.55 also fixes a bug with getting matrix inverses, apparently.
And no, the patch doesn't make the bugs go away :/
