I can't speak for the new versions (i), but I feel like the SR225 with TTVJ flats is just more ... intimate ... more fun. Maybe I have a really nice copy of the SR225, I don't know. The RS1 is a fantastic headphone -- yes, better details, wider soundstage, clearer separation of instruments, better bass extension, BUT, it hasn't been as fun to listen to lately. And yes, there is a price concern there too -- especially when you have a pair of $700 headphones just sitting on the desk unused most of the time.
I usually listen straight out of my iPhone or MacBook Pro, even though I have a decent DAC / MAD Ear+ at home. Maybe I'll have to sit down and compare the SR225 and RS1 further hooked up to the amp.