Hi Carl,
Hey, you've started to use it :-) ! You can keep going with the FIGnition editor beyond 511 bytes, though it will start to get slow at about 2500 bytes or so. Remember, if you edit a block and it gets longer than 511 bytes it'll save it to the next block number, so I would suggest providing gaps. For example, let's say your old source code was on blocks: 10, 11, 12, 13.
You edit block 11 and it gets longer than 511 bytes (but still less than 1024). When you save it, the text will go to blocks 11 and 12 overwriting what was in block 12. The new editor will only save to as many blocks as it needs to store the text though, it won't write 25Kb just because the editing space is now 25Kb!
The T2E2 tool hasn't been updated on this release. It will still split programs into <512b blocks. The reason is because the intention with 1.0.0 is to be able to transfer the entire source code for a program in one go via audio so T2E2 won't be needed for that :-)