How is it sufficient? Sufficient for what? Do you think that their end goal is to get a charge, any charge, on this mid level dealer? Of course not; they want information on someone even more high level.

The penalty for 1 oz and destroying evidence (if they can prove that) is nothing compared to the penalty for 1 kg.

This may sound silly, but it seems like there could be a MythBusters episode specifically on this to prove or disprove how likely these no-knock raids are needed to prevent an effective coverup of evidence.

They could actually make some actionable data for public good.

Well, anecdotally, I've been in a house full of drugs when the cops showed up, and those drugs were gone before the cops stepped foot in the house. Yes, I had a not-so-optimal childhood.

Were they serving a warrant, or just asking questions and eventually invited in?

We had a small party (only about eight people or so) and a couple of us got loud in the backyard. The neighbors called the cops and, where I lived, they were coming in, warrant or no warrant. We knew that, so down the toilet it went.

Interesting. Where was this, and what kind of interaction preceded their entry (if you recall)?

Rockton IL, population (at the time) ~3,000. They knocked, we knew who it was, we ran/dumped. I didn't stick around to see them at the door.

Could you share how this was accomplished?

We chucked most down the toilet, some people ate some.