On paper, I personally as a fan of the bright Grados, I don't like how they proclaim these to be more neutral.
From a technical standpoint these are constructed fabulously and it's essentially a poor man's SR-125 with all the upgrades. I don't own an MS1 and don't have the money to buy one new. Hell, maybe it's just an SR-125 availible to Europe? There are countless threads on the topic but you still have that Grado sound otherwise they wouldn't slap the badge on there.
I still am quite surprised that nobody else wants to step up and educate us fools about these headphones! I've only got a track record of 4 years with these guys,
Just buy the Grado you can afford, if you can afford multiple Grados but are also trying to save money, buy the one that is the best deal. They're all the best deal to me since I don't need an amp to play any of them therefore I saved 200+ dollars. I run all my cans out of my computers sound card which I converted into a decent DAC/amp with opamp rolling and a new power capacitor.
I found 3 grado SR-80's just by Craiglisting. (I just bought one today to recable so it's not showing right now)
http://imgur.com/TAKA4
The SR-80i in Monterrey is a pretty sick deal. I don't have any of the "i" series but it looks like they've resolved the comfort issue with pads that are a hybrid between a bowl and a comfy from the looks of it.
Not a bad price on the RA-1 either if you're into that.
These things are more popular than you think among non Head-Fiers! I see them constantly at school.