Two bikes with compacts and 34/27 gearing and a triple with 50/39/30 and 12/25.

With the Tiagra 12/30t cassette (which I have on one set of wheels and when using the Compact crank) I can climb anything as slow as I like. The 27 does take a bit more effort but is OK. Reason I put a triple on one bike was for those long hilly rides where I just want that little bit "Extra" on the gearing. Initially I used a 12/27 and found the wider spacing on the 3 higher gears annoying and that is why I went to the 25. In theory I should find the same problem with the 12/30 on the compacts but I don't. When you need those lower gears- you need them.

And lower gears- The Tandem has 48/36/24 chainrings with a 12/32 cassette and we need all those gears. Did try a 12/34 cassette but we kept bending the 34 with the power we put out.