Upgradeable Proxies vs Contract Redeploys

Preserves State & Address: Logic can be upgraded while user funds, mappings, and the contract's on-chain identity (address) remain intact. This is critical for protocols with locked TVL (e.g., Aave, Compound) or NFT collections where metadata is tied to a single address.

Increased Complexity & Attack Surface: Introduces proxy patterns (e.g., Transparent, UUPS) with admin key risks and potential storage collision bugs (e.g., the infamous Parity wallet hack). Requires rigorous testing with tools like Slither or MythX.

Simplicity & Security: Each deployment is a fresh, immutable contract. Eliminates proxy-related vulnerabilities and simplifies audit scope. Ideal for rapidly iterating MVPs, gas-optimized contracts, or when using formal verification tools.

Breaks Integrations & User Experience: Requires migrating all state (a complex, risky operation) and forces users, frontends, and other contracts (e.g., Uniswap pools) to update to a new address. This causes significant downtime and coordination overhead.

Enable rapid iteration: Security patches and feature additions can be deployed via a governance vote (e.g., Uniswap, MakerDAO) without requiring users to move assets. This reduces protocol downtime and user friction during upgrades, allowing for faster response to market changes or vulnerabilities.

Introduces new attack surfaces: Proxy patterns (Transparent, UUPS) require careful management of storage layouts and initializer functions to avoid catastrophic collisions. They rely on a ProxyAdmin contract, creating a centralization vector. Audits are more complex and costly, as seen in incidents like the Audius hack (2022).

Eliminates proxy risks: A fresh deployment has no upgrade mechanism, making the final code immutable. This simplifies audit scope and provides stronger guarantees of finality, preferred for token contracts (e.g., ERC-20 standards) or non-upgradable core logic. The security model is straightforward and well-understood.

Complete architectural freedom: Each redeploy allows for a new storage layout, language (e.g., moving to Solady or Huff), and compiler version without legacy constraints. It's a clean slate, ideal for major version overhauls (V1 to V2) where a state migration is acceptable or even desirable.

High coordination cost: Requires updating all external references (frontends, oracles, other contracts), notifying users, and often executing state migration scripts. This process is expensive, risky, and can fragment liquidity and community attention, as seen during early SushiSwap migrations.

State Preservation: Upgrade logic while preserving user data and contract address. Essential for protocols like Aave and Compound with billions in TVL. User Experience: No need for users to migrate assets or update integrations. Gas Efficiency: Initial deployment is cheaper than a full redeploy for complex logic.

Centralization Risk: Relies on a privileged admin (e.g., multi-sig, DAO) creating a trust assumption. Increased Attack Surface: Proxy patterns (UUPS, Transparent) add complexity; bugs in proxies like the Parity Wallet freeze are catastrophic. Tooling Friction: Harder to verify on Etherscan, requires specific testing frameworks like OpenZeppelin Upgrades.

Simplicity & Security: Immutable code eliminates admin key risks. The gold standard for trust-minimized DeFi like Uniswap v2 core. Verification Clarity: Contract source maps directly to deployed address, simplifying audits and Etherscan verification. Composability: No proxy storage clashes; integrates predictably with other protocols.

Migration Burden: Requires users and integrators (front-ends, other contracts) to update to the new address. High Gas Cost: Full redeployment of complex logic (e.g., a new DEX router) can cost 10x more gas upfront. State Fragmentation: Can lead to liquidity and user base splits, as seen during SushiSwap to Trident migration efforts.