You're missing one step there!

You need to BINHACK the boot binary files (usually 1ST_READ.BIN) to LBA=0, because you're using the utopia disc.

So, just use Echelon's binhack.exe and use the LBA value = 0.

btw, please post your results with the Dreamcast reading GigaRec burned discs. It could be really cool to be able to backup full discs without downsampling/ripping anything.