It's 150 meters for class B's, the FCC does everything by meters instead of feet, so its around 492 feet. =)
(The other classes allowed in Connecticut, B1, A are 100 meters (328 feet).) And that height is not the height above ground, but rather the height above average terrain. What that means is, the height of the transmitting antenna over the height of the relative terrain around it. Here is an example. Lets say you had a small perfect circle sized hill around a field. And its flat for miles out. There is a tower on this mountain. The mountain is 50feet, the tower is 60 feet, and the antenna is 50 feet up that tower. The height above average terrain would be 100 feet. There are HAAT calulcators online. And again, its all done in meters. And yes, as the height of the antenna goes up, the power goes down. Remember that FM runs on a theoretical "line of site" principal.
In Hartford, a good pair to look at is WRCH and WCCC. WRCH is 381meters above average terrain, so their power level is 7,500 watts., WCCC is 221 meters above terrain, so their power is 23,000 watts, due to the antenna being lower to the ground. Both have signals equivelant of a 50,000 watt signal at 150 meters. Each have advantages. The higher antenna gets a further outward signal into rural terrain, yet the lower antenna, which has higher power, has better building penetration. As for the strongest signal in Hartford, actual raw power wise, it would be WCCC @ 23,000 watts.
WBMW is going from a class 6,000 watt class A signal to a 25,000 watt class B1 signal. However they will be directional and the signal in the direction of the null will be close to or less than their current class A signal. They are increasing the height above average terrain by 4 meters as well.meters too.