Hi, I own the V8 and have A/B'd with the SE846 before. I actually think the SE846 has more sub-bass presence, while the V8 has more mid-bass and low mids. In regards to bass bleed, there really isn't any at lower volumes. I only turn the volume up for stage use, and the bass warmth compensates for the outside noise so to me the bass doesn't really overwhelm the mids. Unfortunately with the SE846 I only used one filter and I don't know which one it was, but the treble sounded rolled off and dark in comparison to the V8 (so it might've been the black filters). I personally thought my V8 sounded quite close to the universal Roxanne in terms of sound signature (though I don't know what setting the bass dial was at >_<)
They do ship to Australia but I also ordered from a distributor (acustoms), since it was less trouble for me. I only had to go to their appointed audiologist for impressions (I didn't have any impressions yet), and they handled the entire shipping process (so they were responsible in case something happens during shipping). I remember the overall price was slightly less compared to shipping the impressions myself.
There was a slight miscommunication issue with my first order. I originally wanted ambient ports and then changed my mind afterwards. When acustoms sent the invoice it didn't have the ambient port option, but when I got the V6 it did have ambient ports. I wasn't charged for it, so it was all good.
My V8 needed a refit, and acustoms took care of the shipping. It was also past the 30-day free refit period, but I asked 1964EARS beforehand if I could send them later (I wanted to use them for a church conference).