I'd look at why I sold the Emp. Artsy first - if it was because you didn't like the style, while there may be some differences, if you didn't love the Artsy in Emp. what would make you love the Mono one, KWIM? However, if you really regret I'd go for the Artsy.
Also: the Artsy is less common than the Speedy (and more expensive.) Price increases are fickle, but the Speedy will probably always be cheaper. I'd go for the Mono Artsy first, then looking at getting a Speedy later.
I have both the Artsy and several speedies and I would purchase the Artsy as I carry it in my hand as well as wear as a shoulder bag...and IMO its a tad but more upscale than the speedy...but you can't go wrong with either bag...good luck with your decision and I hope you love whichever bag you choose...
i have both mono speedy B and mono artsy but unfortunately i havent used my artsy much, it's a bit too bulky for my daily use ( i commute by train ) though i LOVE the artsy so much and wish i could use more. On the other hand, I use my speedy B a lot, no matter how common or rather affordable price it's very practical, amazing bag !