is 'buy to let' worth the hassle?

I think that is the least of your hassle. [paying CGT]

Its not a hassle but its a real problem. People decide to sell their investment property of twenty or thirty years and find out that its worth 100,000 less to them than the figure they had in their mind (the market price), because of the CGT. The result is that they re-consider selling and hold the investment until death. And an investment that you never cash isnt a good investment. Of course CGT also applies to shares but at least you can sell the shares over a number of years as required.
 
On the basis that we are looking at a single BTL investment....

I can't see how it would not be more attractive to invest the funds in a REIT / ETF invseting in real estate etc - less hastle, diversification, lower costs, liquidity etc.