Owen,

If I've managed to read my lab notes correctly, these were the
differences in loss (ground+feedline+tuner) - with and without an
ideal 9:1 transformer at the feedpoint - for a 33ft vertical over
average ground fed with 50ft of RG213. I assumed ground losses of 20
ohms. Positive figures indicate that the losses were lower with the
transformer:

160m -1.6dB
80m +6.02dB
40m -2.3dB
30m +2.1dB
20m +4.4dB
17m +3.86dB
15m -0.55dB
12m +1.6dB
10m +2.9dB

Of course this data was for one specific scenario, but I guess you'd
look at it and say that for this case, on balance, the inclusion of
the transformer was of benefit. But now factor in some realistic
transformer losses and it might not look so clear cut.

73,
Steve G3TXQ