If my TW-1's were accurate to within 5%, I wouldn't mind, but the one that
is in my HF circuit now is off by about 60%.  Once I realized how inaccurate
they are, I stopped relying on it for anything other than the tone function.
I agree that it is good for tuning an amp, because you are just tuning for
max pitch.  Max pitch = max smoke.
I am troubled by comments I have read on this reflector about 6 to 1 or 4 to
1 SWR being totally acceptable.  They are not.  Solid state equipment with
fold way back on a SWR of 2 to 1.  It must be understood that a high SWR
generates heat, and heat destroys coax.  If a station running a kilowatt had
an SWR of 2 to 1, you risk burning up the coax.  Also, just because you use
a tuner to reduce the SWR as far as the rig is concerned, the transmission
line is still with the original high SWR.  That is, a tuner does nothing to
lighten the load of the coax.  Transmitting into an SWR of 4 to 1 means that
very little of the power is ever finding its way to the antenna.
Personally, I have my PM2 configured to open the amp key line if it sees an
SWR of 1.5 to 1.  Fortunately I use a SteppIr antenna which automatically
maintains an SWR of approximately 1.1 to 1.  I just performed a quick test
on 20 meters.  I measured  1486 watts forward, with 1 watt reflected power.
Since the SteppIr controller follows the frequency of the rig, the antenna
is always in resonance.

73