Is investing in a stock like BRK a tax effective alternative to ETFs?

Tax effective alternative, yes. Taxed as a stock @33% on gains when sold. No deemed disposal rule. Just decide whether you think the holdings in the stock is enough for you. IMO not a bad way to invest passively, but others may differ. Fair to say that Buffet and Munger are in God's waiting room now, that might sway peoples thoughts, if they are still in charge of things at all, that is

Brk top 10 holdings are something like 40% Apple, 4/5 banks, Coca cola, Heinz etc. It's a tax effective option, yes, but not a good substitute for an S&P 500 type etf/investment trust imo.

Currency risk to USD.

Estate taxes on anything over 60k,

Rules it out for me.

The attraction of Berkshire, or equivalents, is avoiding income tax on dividend income, which cannot be avoided on investment trusts.

Many IT's dont give any or very little dividends, compare annual performances of BRK.B to SMT, you might get a surprise, BRK.B isnt the only show in town. IT's (unlike ETF's) are treated the same as ordinary shares here for CGT purposes.

BAM is another US stock that has outperformed the market for many years too.