The producer thing didn't work for the first four albums
Huh?
What BC&SL might have been with an outside producer is obviously nothing but speculation, but the notion that having outside producers on the first four albums didn't work is just crazy.
Except for the 37-year old Charlie Dominici, the members of DT were 21 when they recorded WDaDU (July - August 1988) and had no idea what they were doing (even "Old Man" Dominici had relatively little experience), so an outside producer was an absolute necessity.
Not much had changed when I&W was recorded three years later (October - December 1991). What "didn't work" about having an outside producer? The triggered snare? Honestly, would anyone know about that if Portnoy hadn't so vocally and publicly bitched about it after the fact?
Awake was recorded another three years later (May - July 1994). No triggered snare, so there would seem to be even less basis to say the outside "producer thing didn't work."
That gets us to FII (recorded in June - July 1997). I'm sure we could go on for pages and pages about why this is generally regarded as a bottom 3 DT album (although some folks don't agree with that), but is there really any principled argument that it was Kevin Shirley's fault? Shirley pulled "Hell's Kitchen" out of BMS and made it a separate song. In my book, that's a good thing. Shirley recommended that Desmond Child get involved with "You or Me." Petrucci obviously agreed, and Portnoy even admits that he agreed (albeit because, in his opinion, it was a song that wasn't going to be used anyway). IMO, "You Not Me" is superior to "You or Me," so that's a win for Shirley (and outside production in general). If you believe Portnoy's statement that FII was "a blatant attempt at radio success" (and I don't think Petrucci has ever contradicted that), I think that's the biggest problem with FII (again, not an outside producer problem). Portnoy and Petrucci disagree about the extent to which the record label influenced the album, but I think it's difficult to deny that the label issues the band was facing played a far bigger role in the quality of FII than any outside producer.
So, with all of that, you've got two great albums, a debut album with an extremely green band and a poorly funded record company, and one album whose problems can't legitimately be blamed on the presence of an outside producer.
Given where DT is now, an outside producer would play a
much different role than the producers played 20-25 years ago. While I'm not one of those who absolutely advocate for an outside producer, I think it would be interesting to see what they'd come up with with the
right outside sounding board.