I live in the Hayward Hills (south of Oakland,CA) and there are two hills with >8% grade, and I have a non-turbo 300D so I use the kickdown at least twice a day
By the way, my tranny is beginning to slip in 1st gear on the really steep part of the hill if I am just starting out from a stop. I try to get a run at it and lug up the hill in 2nd.
I have already cranked the modulator up to get rid of a 2-3 flare which made the 1-2 and 3-4 shifts really firm, and the 2-3 firm. I'm kinda hoping I can stick a longer pin in the B2 band servo to eliminate the 1st gear slip, but if all else fails I will be rebuilding a tranny sometime this summer

David
'81 300D odometer says 148,800, but it wasn't working when I bought the car although the last registration in 2003 said 141,000 so maybe it's close to accurate