My immediate collection is now complete. All TI-83/84 family. Only one of them has an up-to-date OS TI-84plus --2.55). I have to consider updating the others (except the TI-83). Having looked through the archived topics on updating OS's, it looks to me that a better idea would be to leave things alone. (If it ain't broke, don't fix it. Let sleeping dogs lie.) Each one except the TI-83 is recently acquired and all appear to be working well. I would welcome some inspired advice as to whether to update.

It depends on how much you plan on actually using them; if they're just part of a collection and you don't plan on doing much, I wouldn't bother.

Plan A is to examine games programmes with a view to learning a little. No serious plans. On this basis, it looks as if your advice is good.

As a matter of sincere interest and the search for knowledge, is there any data as to the success/failure rate of updating Os's ?
Again, looking at the archived posts, I suspect that there is a noteworthy risk of problems. If there is no data, then an opinion would be welcome.

Upgrading ROMs generally causes no problems at all. Downgrading can be problematic, depending on the calculator's age and boot code: the newest calculators, pre-loaded with the MP OSes, are hard to downgrade to a non-MP OS. You'll find that many of us are not crazy about the MP operating systems, especially from a TI-BASIC programming point of view.

Others of us (especially those of us who use the calcs for math) absolutely adore MP.

Thanks Kerm. So we can say that 90% upgrade success can be expected. I have no interest (at the moment) of downgrading. Can I assume that an MP OS could be updated with a similar success Rate ?
(I should add to my signature :- "The search for knowledge is a worthy occupation")

I'd expect it to be more or less 99.9% success, as long as your calculator has reasonably non-dead batteries. And even if things go terribly wrong, in almost every case the bootloader has sufficient safety features to allow you to re-try a failed OS upgrade.

In my investigation into upgrading OS's, I have become well aware of the need to have adequate battery power. It is re-iterated in every discussion. 99% is, for me, pretty good odds. I would gamble (my life ?) at those odds. .Regards.