I understand that the tax perks of UCITS are significant, but I'm worried about the 'hidden' trade-offs over 20+ years. Beyond fees, how much will lower liquidity and tracking errors in EQQQ actually hurt my returns compared to QQQM?

If EQQQ's higher costs help avoid U.S. estate taxes, how should I compare these tax benefits with QQQM's lower fees? This is especially important when deciding between UCITS and U.S.-based ETFs for long-term investments in the U.S. market.