I feed in their enclosures and have never had issues. I use newspaper substrate. No behavior changes either.

The cons of a separate feeding tub are:
1) stressful for the snake
2) you are more prone to get bitten because the snake is conditioned to expect food when you handle it when transferring it to the feeding tub. The snake may or may not still be in feeding mode after it's swallowed its prey and can lead to a bite.
3) This isn't that big of a deal, but you have to handle a snake will a full belly. Extremely rare, but can cause a regurg.
4) Because BPs are known to be shy or picky, the snake may not even bother to eat in a new environment.

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