"The range of the 175W model would be much less than the 250 W version."

Not true. The difference in output is 2 db. The only time there will be a
substantial difference is when you are at the threshold of the 175 watt
signal. The difference between high power and low power would be more
significant at lower altitudes, when you are shadowed from the radar. At
high altitudes, you are more likely to have a clear shot to the radar.

I think there is a balance between power and battery life.

I do not know the significance of the difference in altitude specification
between the two units. The manual clearly states that the maximum altitude
for the 175 watt unit is 15,000 feet. It would be necessary to understand
the reason for this statement before it is prudent to ignore it. It may be
regulatory, rather than technical.

Colin