Same questions over and over, no mater how many people have answered them, in this thread and in countless others.
If you want cold boot, you must be on 4.1 or lower, and save your fuses if you update. Cold boot may or may not see a public release within 5 years. (just throwing out an arbitrary date, since the only thing anyone has ever shown me was a pretty green screen. No WORKING cold boot or warm boot has been shown publicly, and no warm boot method could ever take advantage of this fix, since you'd need to use RCM to boot in the first place.)
If you update while saving fuses, for whatever reason (to play newer games, visit the eshop, etc) you risk a ban, unless you always keep it offline and update your games offline, because you MUST ALWAYS boot with CFW.
If you are currently above 4.1, you can always sit back and hope, but there isn't even a rumor of a coldboot at that stage, so you're locking yourself into CFW-only mode for no reason at all.
The sleep mode fix isn't really that useful unless the pending cold boot method is early enough in the boot chain to actually work, with the extra fuses burnt (so yes, this seep mode fix enables you to use the switch normally with a lower firmware than your fuses say, but again, it locks you into a CFW-ONLY mode, via RCM).
The best solution for me, personally, is to always be up to date, because I am not banned, and I can visit the eshop, download game updates and DLC as intended for all of my legit games, and since I use SX, I have emunand (with Ninty blocked in the DNS) to play with homebrew and .NSPs and such.
Another option, if using a dongle is simply too troublesome for you, is to solder on a trinket or something and you can have cold boot right now.
Your choice.
P.S.
Funny thing is, unless the cold boot does eventually come out, and does work early enough to patch out the fuse checks from a coldboot, this sleep fix is actually more useful for emunand, than it is for any other free CFW. Because if not, there is absolutely ZERO reason to downgrade in the first place (assuming your fuses have already been burnt above 4.1)!