So this confirms that we really do can? Thanks for your answer. And you're right, it's really tedious, however the only update cart I have is FF Explorers which update US 3ds to v9.9.0, I'm constantly installing a9lh to friends, relatives, & colleagues, and if I were to encounter a 3ds with fw 1.0.0, I don't have a cart that can update it to 4.x.x or 6.x.x. I'll already be lost there in the beginning if I can't update it to v9.9.0 first, downgrade to v.9.2.0, then proceed to installing a9lh.There's only one cart with 9.2. Making a guide for that one game seems a bit tedious and overdone. Without the original Super Smash 3DS cart, you can't just install 9.2 on 1.0 3DS. Ninjahax, and alternative entry points can only run unsigned code in firmwares 4.0.0-7 and 9.2.0-20.
So how exactly would you update to 9.2?
Edit: Using an update via game cart, unless it's Super Smash, requires more steps as you'll have to downgrade to 9.2. Going from 1.0 to 4.x-6.x allows you to not only keep the low system version (in case you want it again in the future for some odd reason) but allows you to use MSET which is easy peasy. I guess the rule of thumb is to get to the lowest possible exploitable/vulnerable firmware and then proceed. Since we don't need to be on 9.2 before doing ctrtransfer, why bother?