They're still signing iOS 6.1.3 for iPhone 4s.
According to ipsw.me, yes - and also 6.1.3 for iPad 2 is being signed. However, according to Neal's TSSstatus API (
https://api.ineal.me/tss/status) 6.1.3 is not signed for either of these devices. Not sure which site is correct in this manner - ipsw.me claims to fetch data every minute from Neal's TSSstatus API however they appear to be completely out of sync.
On a side note, they have now started signing every single 11.x version for all devices that support iOS 11, according to
https://api.ineal.me/tss/status. See the attached examples of signing status for iP5S and iP7. However, according to ipsw.me only 11.2.x is signed. Oh, who to trust?

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[doublepost=1515691645][/doublepost]The downgrading debate is interesting. On one hand -
not allowing users to install older firmwares effectively kills off OS fragmentation which has been a huge problem in the Android camp ever since they first started making Android phones, due to the fact that all Android phone manufacturers have their own heavily modified carrier-specific OS version and so on. This makes life easier for developers since they don't have to work with outdated software frameworks such as the SDK for iOS 6. It also improves security for users since you are unable to install an older version of the OS which might, perhaps unbeknownst to you, include fatal security holes such as Spectre/Meltdown.
On the other hand,
allowing users to install any version of iOS just as users can install any version of OS X or Windows on their computer (given that the computer's hardware technically supports that version) means giving users a choice. Perhaps your device is used for a specific purpose and using an older firmware gives you the performance advantage you need - for instance, I have an old 3GS which is solely used to play music on a Bose speaker system with a 30-pin dock; I barely ever take it out of the dock. I keep it on iOS 4 because the Spotify app performs waaaay better on the older firmware than on iOS 6. However - I were to use it as my actual everyday smartphone, I'd put iOS 6 on it and take the performance hit just to get access to stuff like iMessage, iCloud syncing etc. Or you might need to run an older app which hasn't been updated for iOS 11 compatibility, for personal or professional use. Downgrading firmwares could also be of practical use to developers who want to make sure that their app runs the same on every iOS version that it supports - I think you can do this with the iPhone simulator but if I were a developer, I'd sure prefer to test it out on actual hardware running the iOS version in question. In this case, every coin really does have two sides
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