Ethan Leib, of Prawfsblawg fame, has put out a work in progress in which he proposes supermajorities rather than unanimous decisions for convictions and simple majorities for acquittals.
I haven't yet read the actual article but must say my gut instinct is to oppose this sort of change.
(A) There's no problem to solve here. Both from my personal experience and discussions with other attorneys, I believe there are very few hung juries. Juries almost always come to a unanimous conclusion.
(B) The objective of the system is to put the onus on the government. Not requiring the government to prove its case to the satisfaction of 12 citizens is a step back from the burden of proof. In effect, it gives the government extra strikes from the jury pool. If the required number for conviction is 8 the opinion of the last 4 is irrelevant. The government gets the benefit of the 8 jurors it would prefer present (the convictors) and gets to ignore the remaining 4, basically discharging them from their duties because they do not agree to convict.
But wait, you say, the defense gets this same benefit! In effect it gets 5 extra strikes in cases wherein the jury votes to acquit (7 being the number needed for a majority out of 12). Yep. But there's no lessened burden of proof because the defendant has no burden of proof. And, let's be honest here, how often is the holdout minority a couple of convictors when the rest are for acquittal?
Additionally, as a matter of judicial efficiency, there's a good argument for simple majority acquittal: A simple majority for acquittal would benefit a system which requires the government to prove its case by keeping the government from retrying weak cases.
Anyway, I suggest that ya'll go download and read the article. For all I know it blows my reservations out of the water. I'll try to comment on the article as a whole when I get a chance to read it.