I have owned both now. Time to compare.
They are essentially the same headphone, with a couple of minor differences. First off, they look identical except the MS1i's have different lettering on the earpieces, and they don't have the little button on the middle of the grill. Everything else is the same. Same plastic, same earpads, same cable.
The high-highs on the MS1i's are a tiny bit better - more rounded, less harsh. But the SR80i's aren't really harsh. Maybe a tad. The lows are about the same. Deep and punchy. But the MS1i's are a bit clearer all around. I can pick out little details on songs that I couldn't with the SR80i's, which are very good in this regard. So I'm going MS1i in sound quality over the SR80i, but only by a teeny tiny amount. I believe the MS1i's leak a bit more sound than the SR80i's, but they're both in the same catagory. They both leak sound like you wouldn't believe. I find the MS1i's are a bit harder to drive, but it might be my imagination. I have a Luxman R-113 reciever with a built-in headphone amp and the drive them easily, but I have the volume up almost to maximum on my laptop. The SR80i's were pretty good on my laptop. My iPod Nano can handle both headphones with no problem.
But here's the crunch for you fellow Canadians out there. The SR80i's, after taxes, are almost $200 here. The MS1i's are $99 with free shipping, no duty, and no taxes. I don't know why there are no taxes. Maybe because they ship from "George Alessandro" which doesn't look like a business at all. We might have fooled the taxman, I don't know.
I ordered them last Thursday, and got them the next Wednesday.
So, the bottom line: I recommend the Alessandro MS1i over the Grado SR80i if you live in Canada. The differences between the two headphones are minor, but the difference in price is huge.
They are both excellent headphones in my opinion. I personally have no need or desire to up in quality unless I win the lottery.