Great sharing dude! I just want to be clear that I am not in any way putting down or bashing the RS-1...nobody in their right mind would. The RS-1 is what it is. A timeless legendary in its own rights. I owned one in the past and I am still proud of it. Over here, people still flinch when you tell them you have (or had in my case) a RS-1
The difference between the RS-1 and my Cocobolo 325 is not night and day. Remember that my buddy and I took 5 painstaking hours before making the impartial decision and we're both die-hard RS-1 fans alike.
Now, even as stock cans, the SR325is already does one or two things better than the RS-1 thanks to its aluminium shell and extended or prominent highs if you will. To me, what it lacked then was the smooth organic mids, the depth and lows of the RS-1. With the hole punch mod, it levels things up by quite a jump and top that with cocobolos, the missing organic piece is achieved. Aside from tracks that has stronger emphasis on the mid bass, the cocobolo 325 matched the RS-1 all the way. I don't know if the cocobolo is doing its job (and I think it is) but it just has better bass slam and depth compared to the RS-1. However, yes, however, there is still this magical note on the vocals the RS-1 make that is still somewhat superior. The thing is, right now, if I had to choose between a RS-1 and my cocobolo 325, I will honestly tell you that the RS-1 is no longer a choice I would make although, glamor sake aside, I would still want one for that occasional magic touch on the vocals which only the RS-1 has. I believe if you take the RS-1 drivers and have them fitted to cocobolo shells, they could just very well be perfect!
Like you, I cannot say if the same is achieved using a SR225i as base. If anything, the 225 was the only Grado in the Prestige line-up that I have not owned / listened to. So, it's zero experience for me when it comes to the 225. People smack me for that as they say the 225 is probably the finest Prestige can. That's really debatable since sound is very much a subjective thing. Still, from what others have told me, I won't form a judgement on the 225 until I have listened to them for myself.
Off the record, I even had the 325 goldies and those were even more prominent in the highs. Me ears bleed I tell you...and they bleed bad. Grado had it tamed down, if ever so slightly, with the newer IS models. Heh, your friend is a lucky guy to snag your cans off you. Cocobolo 225! Christmas came early for him eh?