I added the gravel ores from Tinkers' Construct to the config file, and they generate fine, but I've found a few flaws:

• The block breaking sounds are stone
• It takes far longer to break with a shovel even though it's the right tool
• Breaking it with a pick is faster, but drops no ores
  Not a huge issue, but something to look at.

I noticed this as well.

And it also doesn't fall down like normal Gravel does.