MUEP is 3 hours per week on one day and UMEP is 4 hours per week but spread over two days. So that depends on how much time you're willing to spend travelling to and from.
Also MUEP is $900 all up and I don't know about the fees that UMEP charges, but I'm relatively certain it'll be free (the career's lady at my school rang up and asked for Psychology and they said there's no fee and since Jap isn't being held at school centres, it should be the same. but then when I went on open day which was before the phone call, the co-ordinator said they might charge a similar fee as MUEP). However, they haven't updated their bloody page and fees would be the only thing that's stopping me. Ahh, frustration.
But, anyway. Personally I would say go for UMEP because I'm biased. The 5.5 shouldn't be too hard if you've got such a keen interest in the subject.