Don't take the word of one reviewer so literally, or so precisely, or (more importantly) as one that will necessarily match your own preferences. Reviews are one person's opinion, from one person's perspective/reference, & coloured by their own personal preferences. No one's opinion, no matter how respected or prolific, matters more than your own experience.
I've heard the very headphones used in that review, as the current owner is a well-known member of the NY Head-Fi contingency. I, personally, would never use the word "bright" to describe them, either in the absolute sense, nor even relative to other warmer headphones. To me, these modded cans fall into the warm & lush side of the sonic spectrum compared to my neutral reference (Etymotic ER4). They sound very nice out of a properly matched amp, which (again, imo) is a fast, neutral solid-state amp. This only underscores what I stated above, as the previous reviewer typically prefers tube amps.
If you are so interested, do yourself a favor and find a pair of modded pair before passing judgement. Love 'em, or hate 'em. Lust for them, or can't justify the price - no problemo. But nothing is as worthless around here as a vehemently stated opinion that has absolutely no experience to back it up.
Sadly, I won't be able to get a hold of an already modded pair to test out (looked around locally), so I'm going to have to go off of opinions, but I'm thinking that I'll side with what seems to be the majority opinion on this one.
The vast majority opinion seems to be that it improves the sound quite drastically, and I've never seen anybody say it sounds worse, at least not on Head-Fi, only that it's better or "better with some songs, worse with some".
Looks like it's time to start putting money away.