@KevinTheGerbil :-
Hi, Kevin.
O-kay. Well, unlike @houndstooth , although my Xenialpup64 - like ALL my Pups! - IS heavily modified/customized, all those alterations are confined to the 'save'. And all apps, including multiple different builds of portable-WINE, are ALL 'portables' linked-in from outside Puppy.
Unlike many who customise, adding in stuff they like and/or specifically want before eventually creating a re-master, I prefer to keep the basic, 'vanilla' Puppy underneath as original as possible. With the exception of the upgraded glibc, my Xenialpup64 'base' SFS IS just that. This was the main impetus behind development of the portable eco-system, along with creating as many of them as I could, because it's allowed me to create scripts which can set-up a brand-new, vanilla Puppy install to fully-customized status in a matter of minutes. I no longer "install" stuff; instead, I merely 'link-in' stuff from outside which is already fully set-up.
I guess my set-up IS probably unique, even among Puppians (most of whom are nothing if not extremely inventive!) But it 'works' for me.....works brilliantly, in fact. And so I try to share some of that uniqueness & incredible flexibility with the rest of the community.
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With regard to downsides connected with the glibc upgrade, so far as I can tell there ARE none. Leastways, none that I've yet discovered.
So far as construction is concerned, I've taken the path of 'least resistance' (like I usually do). I haven't tried to upgrade via installation of a series of updated packages from the repos (well, I tried it once, with battleshooter's glibc 2.20 upgrade package she built for Carolina/Saluki. It worked very well for Racy, Precise & my old favourite, Slacko 560; same generation, y'see. But it was still a bit clunky.)
I ended up using the method that watchdog pioneered a few years back. Darry and I were messing around with his updated & re-built/modernised Puppy 4.3.1 (the "Phoenix", as he'd christened it). We were having the perennial problem that always rears its head with such elderly Pups.....that of getting a reasonably modern browser to work.
watchdog came up with a method for utilising a self-contained , newer glibc. Quite where he found the inspiration from, I couldn't say, but by experimentation he'd come up with the basic, stripped-back, minimum set of components necessary for such an endeavour to fully function & do what was required of it. It was called from the launch script when you fired your browser up; he used Pale Moon, of course, due to its light weight and decent performance. It worked OK, though not quite as well as we'd hoped, mostly due to a whole bunch of other components in 431 being really too old. It was then that he came up with the notion of using an entire, basic, newer Puppy as as a chrooted 'jail', allowing a modern browser to function within a matching modern environment.
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Many Linux geeks have used a chroot environment over the years; it's not a new concept, by any means. But where others needed to strip-back a mainstream OS to its bare minimum, Puppies are tiny enough that you can get away with using the entire thing, as-is. watchdog used Precise for this.
I ended-up putting together a self-contained package using a Tahrpup chroot, and running the then-current Iron 69 browser, loadable via SFS. It was rather 'chunky', I confess, but it let us run a bang-up-to-date Chromium-based browser in a truly ancient Puppy. Darry was so impressed with this, he was all but speechless! 
I've maintained a pair of chrooted Puppies on an external HDD ever since, updating the 32-bit one as far as Xenial32, whereas the 64-bit one has migrated from Tahr64 to Xenial64, and eventually Fossa64, I might take the 32-bit one to Bionic32, possibly further. We'll see how the fancy takes me.
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I've used watchdog's method to construct a whole bunch of glibc 'upgrades' over the last few years. I have 32-bit upgrades in
In 64-bit, I have
Haven't been able to find anything newer in 'non-usrmerge' format.....but these work very well for me.
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Anyways; here's the bit ya want.....at long last! You can find the upgraded Xenial64 'base' SFS at my MediaFire a/c, here:-
https://www.mediafire.com/folder/6v863d ... enialpup64
I've also included a wee script which, when you click on it, will display the Puppy version, the kernel in use, and the 'installed' glibc in a gxmessage window. It's a bit of frippery, TBH, but it is useful for all that. I keep mine on the desktop, hidden via an invisible PNG icon. I know where it is, but nobody else would! 
I was experimenting & playing around with sed, awk & cut; early days, yet, just to see what was possible with 'em. That's why you have the stuff showing what time the info was 'fetched', along with the date, etc. 
Just swap the SFS with your own, and re-boot. That's all that's needed. The wee script will run from literally anywhere.
Let me know how you get on with it, please.
Mike. 
