With pulsonic M25's I agree 110%, but I think the perception many have of the H25's & M20's being less tight might come from the color of the cabs themselves they came in typically and would agree about how the sound translates there, but I've compared (both isolated (not in a cab) and in some of my different cabs) all the various H25's & M20's I've had to my other speakers (including V30's, Redback's and Blackbacks among many others) and actually found them to be some of the tightest and fastest responding speakers I have out of 70+ speakers I currently have with a wicked chainsaw-like upper mid grind that makes them tied with Altec 417B's as my all time favorite speakers. Because of their very lean/thin low end I find for metal I need either a beefier, more robust sounding cab or speakers paired below (such as Crescendo's or JBL's like EVH did) and then it becomes among my favorites for metal too, but maybe not for some specific metal styles. In some ways they can almost sound like a 10" speaker with how fast, crisp and lean they sound, but I love them to death. I find the heritage reissues also do a great job capturing their overall flavor, but not as raw, 3D and the big difference is also much quieter
I love my redbacks, but never found them tight or fast and with low mid heavy amps like my Recto’s, Uber or Blueface they can get flubby IME. I find them to complement well either my very tight or bright amps like my Hermansson or Hell Razor (great combos there). Blackbacks I never cared for (I have a quad still). Something about their midrange I find ugly/less musical sounding and lack upper mid aggression for my taste like I get in M20's or V30's. Even though I sold them I actually even got metal sounds I liked with the '60's Alnico Blues and Silvers I used to have. When AB'ed (both in a cab and isolated) I thought they smoked the RIC's in every way and is the reason I sold them. I again think some guys get ideas about how these speakers sound from the color of the cabs they come in typically or amps like Vox's they get paired with, but having played my IIC+ (coliseum version as well) through a quad of those in my cabs as well as M20's they can be really cool (imo at least) for metal too (and certainly among the most 3D harmonically rich sounds I've had, which is the most valuable part for me), but I know it wasn't the smartest move pushing those speakers with amps like that in retrospect lol. Especially playing shreddy or sweep type leads with the IIC+ through those '60's Blues or Altec 417's is a sound like no other IME. Maybe the most glorious liquid high gain lead tone I've heard, especially with the Klon boosting it to top it off
That's were I say my taste for speakers are completely different than yours. I don't like most fane speakers, original Crescendo being one of the worst sounding ones in my book, unless if you're playing David Gilmour clean parts. I also hate the JBL series, unless if you're going for that SRV tone. For metal, in special extreme metal with very high gain amps, I can't stand them at all. Even the EVM-12L, which is an incredible overall speaker, loses for most Celestion, when used in a high gain situation.
I also don't like mixing speakers at all.
I agree that the Heritage series, both the EVH and the 20M are incredible sounding speakers, and get very close to the original ones. So are the Scumback versions of them. And both the Heritage and Scumback speakers had more low end and the low end on them were tighter than with the original 20M and 25H I own. That's the advantage of having something with a new cone vs a 50+ years old paper cone.
I've also never liked the Celestion Alnico speakers for metal. Not the Blue, the Ruby, the Gold or the Cream. Let alone the old Silver, Grey or Blue ones! I think these are some of the very best sounding speakers ever, but not for metal. But hey, Reza loves his Alnico Cream to death, so I understand you might like the old Alnico speakers for Metal too. And that's ok.
Now, for my taste, which is completely different than yours, if I could only have a single 4x12 cabinet, I would take a 75 Marshall 4x12 with Ric cones(25m, 30h, 55hz or 75hz) over anything with JBL, Fane, EVM, Altec or any Alnico speakers.