System of a Down - Toxicity has since moved into the RYM top 50 and Dismember out, but looks like the other 49 are still there. I've seen just over half of the bands in concert, including Deftones sucking at a festival and Neurosis not living up to expectations.
12 albums I've never heard in full: Symbolic, Blackwater Park, Jane Doe, Human, None So Vile, Through Silver in Blood, Storm of the Light's Bane, Ghost Reveries, White Pony, Ashes Against the Grain, Those Once Loyal, Like an Ever Flowing Stream.
I think I only own 5 (Black Sabbath, Ride the Lightning, Master of Puppets, Sabbath Bloody Sabbath, Seasons in the Abyss). My preferred format for consuming music has been mp3 for a long time, though I actually pay for some of those now. I could probably find Toxicity and a couple of the Maiden albums in this house since my sister's stuff is stored here.
A few of the albums are in my own top 50 list (any genre):
Black Sabbath - Black Sabbath (#4)
Megadeth - Rust in Peace (#23)
Slayer - Seasons in the Abyss (#29)
Metallica - Ride the Lightning (#35)
Black Sabbath - Sabbath Bloody Sabbath (#36)
Can't complain about some of the other entries. Boris at Last -Feedbacker- is my fav Boris album of the ones I've heard. Love that shit. Altars of Madness is my fav Morbid Angel album.
Sad Wings of Destiny is only my 6th fav Priest album. Filosofem is listenable but not list material in my books.
I prefer Electric Wizard's s/t and Come My Fanatics... over Dopethrone, but it's still iconic enough to be there I suppose.
Individual Thought Patterns is probably my fav Death album but I haven't really fleshed it out. Beyond that, I was only inclined to listen to Spiritual Healing and The Sound of Perseverance in full. From my limited impressions, I'd put Spiritual Healing above TSoP.
Other replacements I'd make:
...And Justice for All over Master of Puppets
Melissa over Don't Break the Oath
Celestial over Panopticon. I can see how people prefer Panopticon as it reminds me of Neurosis a lot, but I couldn't get into Neurosis beyond a few songs. Celestial is more uniquely Isis.
Converge is easily the worst on the list, never liked them. When bands like that were touring here and I was going to lots of concerts, I'd always check them out and usually decide what the hell, might be fun. So I find it funny that I've seen and enjoyed some similar bands such as Ringworm, Doomriders and Cult Leader, but stayed well away from Converge.
Mastodon was good in concert back in 2007 but the vocals really grate on me if I listen to them much.
I listen to some RATM, FNM, AiC, Tool & Kyuss but I have those bands filed under rock and in some cases maybe neglected them a bit. Need to revisit AiC more anyway, they were awesome live even without Layne.