Well, so long as your husband is happy with his job, that is what counts in the end. Just watch out he won't get burned out...that can happen without sufficient breaks and time off every now and then. Make sure you set time aside with him for an occasional holiday to recharge batteries. I've seen friends who work in the finance industry who endure insane hours without breaks, and some of them get burned out soon from that...although touch wood that won't happen to your husband.
Back to topic, Discovery Bay would not be a good choice given the hours your husband work. It is certainly a nice area to live in, but commuting can be an issue. Best to find somewhere on HK Island or in Kowloon next to the Tsuen Wan line (which goes to Central-and Lan Kwai Fong).
And yes, you can certainly keep more of what you earn here in HK!