I'd look at the thread : RSI Pressure Trace and Chrony from July '06 for some extended discussion with the usual suspects including especially from Mr. Oehler.
Fr Frog, noted Scout fan, has an extended writeup on his own experience
Notice for the money involved must factor in the repeated cost of strain gauges although a given wire can be left on the same rifle for an extended period. For some it may still be a no brainer. Later innovations such as predicting preferred exit points - barrel harmonics - joined with the current interest in barrel tuners might for all I know make the RSI gear a necessity for accuracy shooters.
