Originally Posted by Sprognak

Ok, so with my own 3.0 SHSH blobs and tinytss - can I use that to generate signatures and flash to any firmware from 3.0 upwards?

No. If you have 3.0 SHSH you can only restore to stock 3.0 or whatever Apple is currently signing. Anything else must be a custom firmware.

Most likely if you have chosen make my life easier in Cydia then you likely have other SHSH blobs backed up there.

Ok, so basically I can sign my own 3.0 stock, or upgrade to 3.1.3. If I upgrade to 3.1.3 I can downgrade again to 3.0 using my own tinytss blobs.

The above I'm assuming is stock firmwares. Now let's say for arguements sake that I make a custom firmware using pwnagetool etc. How does that differ in what I can/can't install?