Don't forget that Westmere Xeons don't work with MP41 firmwares, this is your main issue.
Of course there is no work-around with the firmware constraint, and I know exactly who to come to should I find that Leopard will work on Westmere!
I'm with
@jscipione - there is a lot lost / gained between leopard and snow leopard.
Leopard is the OS that made me switch, with help from Vista. I was so eager and excited for Snow Leopard that I was running a beta the second I could get my hands on it. Then it was released and my memory is only trouble from there. Incongruent OS, REMOVING functions, old software not being updated for compatibility, and so many bugs that have, to this day, not been resolved.
When I switched to Leopard, I felt like I was moving smoother than a high-fiber turd. Things worked as expected and were consistent throughout the OS. I clicked something, I got results. Things worked. They worked consistently and as expected.
Then, as soon as 10.6 came along, I became concerned. Sure everything moved faster...when it moved or when I could find it. Why did Quicktime become nothing more than a viewer/recorder? I kept QT7 for literally as long as the most recent OS could support it. I always had two versions of iMovie because when I got the one that was released with SL, simple functions just BROKE and were never fixed. Simple things, broken for no reason. Why add complexity to the Finder? Leopard Finder was perfect, for what it was. I'd rather have the Finder do what I want, what I expect, and how I expect it than to have the few conveniences that came with SL.
I would rather have a car with NO auto-driving function than one that ONLY works on a sunny day, with freshly painted lines, with no road patches or rumble strips or tar snakes.
SL had so many micro-bugs that I always had a Leopard partition on my MBP. When I had to burn a CD or format certain drives, there was NO option to get it done in SL so I would switch over. These bugs have yet to be fixed. I'm not kidding. Mavericks, Mojave, Catalina, Sierra, High Sierra etc. still have the same bugs that prevent certain Disk Utility functions that worked in Leopard! Hell, even when I tried to burn a CD in 2015 I had to dig up a Leopard machine! Partitioning a certain drive didn't work in Catalina so I had to use an older machine just a few months back.
HELL, I specifically remember being upset with how adding Siri killed the simple voice commands of the Music player on the iPhone/iPod because the simple commands did more than even Siri can! Of course, the function was limited to music and asking what time it is, but at least they worked!
I can not stand "moving for the sake of moving". Some people judge progress by how far they've moved. I judge progress by the DIRECTION they've moved. Since Apple started it's yearly cycle of all of its products, things have really turned south. I'm keeping an iPhone with TouchID and a hand-sized form factor to the bitter end. I didn't agree to this size-war or collecting lenses on a phone. If Apple could exercise patience and run one OS for at least TWO years while developing the next, I'd have that much more confidence in upgrading. I'm not talking "tick, tock", I mean HOLD THE LINE until things get worked out. Leopard was that OS.
Sorry, I just have to rant every time I think about SL and what happened since.
I'm hopefully paving new roads for people that are restricted to or simply choose to use 10.5. Every hurdle that Leopard has is bandaged by moving to Snow Leopard for 90% of my search results on Google. That makes Leopard users a marginalized group. Rather than solving the issue or receiving assistance, they're simply told to stop living THEIR truth and "go with the norm." I even asked for support from a certain popular modder/developer and his suggestion was "Just move to Snow Leopard, it's so much better."
I'm taking your information and seriously considering it. I was just using SL for a few things the other day and I have to admit there is so much to gain by moving, but I have to be certain that I exterminate the niggles. Basically, I will switch to Snow Leopard if, after sufficient testing, I do not say to myself "well it worked on Leopard" even once. From past experience I have very very little faith that that is the case, but I'm willing to give things a fair try.
Everything you listed will go into my main write up and even opens more avenues of exploration as I go.
I'm hoping to form some sort of repository for Leopard support. I've cruised and searched and scoured for 10.5 versions of things, and I want to save everybody that comes after me from the same grind. (Searching Google for anything Leopard ALWAYS returns Snow Leopard. Man, I hate the name Snow "Leopard" every time I see it now). If I can find a server to archive what I find, that would be ideal. Chances are, though, that the best I can do is provide direct links and hope the dev doesn't remove the file. I will have a personal archive, though, to prevent things being lost to time.
For instance: anybody have Black Magic Disk Speed Test for Leopard? I remember it did exist. Oh, that's right. We switched to the App Store, so now volumes and volumes of data and applications are purged without a trace.
All of those moments will be lost in time, like farts in wind.
