No, the flashrec backup isn't anything important so, without a nandroid backup, there is no way to recover your original firmware/data. In stead you'll just have to install it again using one of the .exe updates from HTC.
Although in your situation, if you're not happy with the buggy 2.1 ROMs, I would install Modaco 3.2. It's exactly the same firmware as your phone came with originally, but much better performing.