Hadn't considered the sensors in lancemates' mecha, but I'm not sure if they're taken into consideration or not. If you haven't had much trouble yet, maybe you'll be okay... but I'm not sure.
Yeah, GH in general doesn't have much in the way of terrain mixing like you described it, and I don't know whether submersion actually makes any difference besides applying some targeting penalties. Mecha scale urban combat, meanwhile, is only really explored in the second game.
About the DP thing: Generally speaking, you're right. It's very rare to see a sensor damaged but not destroyed. That being said, I don't think it's worth the cost savings and extra dp (see note at bottom) to totally skimp on sensors and go with Class 1's all the time. Keeping your SE rating at or over 0 is usually a good investment.
Note: In my earlier comment about 'low grade sensors do have more dp' I meant more dp than their high grade counterparts. This is done, evidently, to reflect an inverse relationship between mechanical complexity and ruggedness. In any case, the formula only makes so much difference, what with all sensors being SF:0 in the first game.
