I play Acol 4NT with all my partners and it has served me well on several occasions, but not the last time it arose.
I was sitting in first seat holding (yes, this IS what I held) the top 10 diamonds and 3 singletons. I know the opponents were not vulnerable, because I feared they would enter with a major. I wanted to open 4NT, but there is no response to cover 3 aces, just 0, 1, or 2. So I opened 1D -- and my LHO passed (WOW) and partner bid 2C (WOW) and RHO passed and partner had 3 aces, so 7D was a laydown. Many declarers were down 8 or 9 when they bid a NT slam. Guess who was void in diamonds
I suggest that if your partner opens an Acol 4NT, bid at the 7-level with 3 aces. I recommend 7C to allow partner to do whatever he wants to do -- you told him of your 3 aces.
I think that would have solved my problem without having to worry about a sacrifice getting in the way!