Aes mods...serial # question

So I got my hands on an AES system with a fairly low serial # 015267. I noticed that certain numbered systems were harder and/or easier to mod. Does anyone have any specific information concerning the differences about them??

there were 2 main PCB layouts for the AES, the old gen board was the first one. Then there is the new gen board (with various more minor hardware revisions of it- AES3-5,3-6 etc). Mine is the new gen layout pcb, so it's harder to mod the bios with a Unibios (using the easier piggypack mod), as the cart slot door will knock the piggybacked bios out of its socket. The earlier gen board doesn't have this problem as the bios is in another spot on the board.
The earlier serial systems like the one you've got, have better RGB output, so there's not so much of a need to do the direct RGB mod on them. But the direct RGB mod will still improve the RGB output, whatever serial number AES you've got.