I, personally, am not up to it yet but a lot of my friends have completed AMus. Whether you'll enjoy it is highly dependent on how much you like to play and practise. It's definitely something to look forward to in terms of repertoire as majority of pieces sound amazing when played properly.
Things to consider:
- You seem to not have mentioned doing Certificate. I know some people skip it as it is very similar to grade 8 but the point of it is to get you accustomed to playing in a recital-like way where you play for a longer period of time. Skipping it may result in being unfamiliar and uncomfortable with playing the 40 minutes required in AmusA. If you feel like this is irrelevant to you, then no worries.
- You need grade 5 of musicianship/theory
- No technical work. Despite having no technical work, you still need to practise basically all the major/minor scales and arpeggios (dom 7ths, dim 7ths etc) to develop and maintain technique.
In conclusion, AmusA seems amazing and I've been looking at some of the pieces in it which are absolutely beautiful.
- Waltz in E Minor (Posthumous) - Chopin
- Russian Rag - Elena Kats Chernin (Popular Music 2 choice)
- Pathetique Sonata - Beethoven
- A few more whose opuses I can't remember (Mainly Chopin ones)
So yeah, you should definitely do it if you enjoy playing the piano. Seeing as I think you're doing actuarial studies, if you do AmusA you'll probably be working on it a lot in the holidays (as you'll be very busy!!!). All the best.
With the shift of Grade 8 from being Level 2 to Level 3 now the performance standards expected right now are closer to AMus not than it is to Grade 7. So perhaps, the only thing massively different is, as you said, the increase lengthiness of the repertoire.
Theory is boring but yeah I know. I need 4th grade theory for Grade 8 right now and I know it just goes higher progressively. With the technical work though my teacher has mentioned that she does always force you to play one scale/arp to get you going, but most of the time we just use Hanon to train ourselves.
I played Pathetique Sonata Mov. 3 as an extra for Grade 7. It was awesome (although my playing was, of course, only good for a 7th grader; would've failed AMus with that)