Slight correction in that it could be your discretion depending on how many gold bars you have. If your on your Jack Jones i think its down to the individual.
You also could not go down to 10 hrs in the hotel as then you would need to add an allowance for travelling time from your horizontal position in bed to the briefing room and vv. So in practice even if you wanted to reduce your rest your looking at 10.30. The Inspecting Officers also pick up cases of reporting then being airbourne 30 mins later, which in effect means you sneaked in early to report!!.
CAP371 is clear as a bell on rest, gets a bit dodgy on split duties with rest earned between 10 and 11 hours but apart from that most straight forward. A lot of the airlines these days are totally reliant on computers so if it says legal dont query it atittude from junior staff who dont know the rules. There is a FDP calculator going around which is used a lot, written by a Monarch Nigel I recall.
OC41 "where's my pencil"