Bitcoin core developer Peter Todd advises users not to accept transactions with less than 6 confirmations after BIP 91 Activates.
Bip19, which was reached and agreed upon by about 81% of miners, has been agreed to be activated.
Todd quoted that
if/when BIP 91 activates, there’s a high chance it’ll lead to multiple reorganizations. Do not trust one confirmation transactions for now; wait for six+ confirmations.
While keen on the potential issues the activation might cause, Todd stated that problems likely to occur, such as double-spending and other related issues, will be fixed after the activation and adaptation of BIP91, which might not take hours or days, so users should not be worried about it.
With exceptions of
1) If you can use other means (e.g., legal system) to secure payment.
2) More technical users who can monitor the chain in detail.
3) Situations where actual losses in the event of non-payment are tolerable (e.g., purchase of items like music with zero marginal cost).
Want to know more about Peter Todd?
Peter Todd is a Bitcoin Core developer and an advisor to Coinkite.
Todd submitted his first bit of code to Bitcoin Core in April 2012, and today is #11 in terms of total commits to Core’s GitHub repo.
BIP 65 added, “a new opcode (OP_CHECKLOCKTIMEVERIFY) for the Bitcoin scripting system that allows a transaction output to be made unspendable until some point in the future.”
In simpler terms, “OP_CHECKLOCKTIMEVERIFY” allows you to send money that cannot be spent until a specified future date.
Opt-in Full Replace-by-Fee Signaling (BIP 125)
BIP 125 explained opt-in full-RBF. Transaction fees are rising, and opt-in full-RBF allows senders with stuck transactions to send a new transaction with a higher fee. Opt-in RBF was merged into Bitcoin Core version 0.12.
BIP 63
A BIP by Todd titled “Stealth Addresses” has been assigned BIP #63 but has yet to be published.