I'm looking for some help about making perk-trees legendary. Specifically, when to do it, with what, and what are the upsides and downsides to doing so?

My character is now level 49, and I've reached level 100 in smithing, Light armor and Sneak. These skills now give me the option to make them "Legendary".

As far as I know, this will give me the perk points back that I've been putting into the trees, but it'll set them back to level 15.

Does this mean, for example, that I won't be able to make Dragon scale/bone gear any more when I do this on Smithing?

Will my Sneak skill become completely useless until I level it back up again?

Besides the ability to put the points into other skills, are there any other things this is useful for?

What skills lend themselves to do this with and what do I have to take into consideration before making a skill tree legendary?

Does this mean, for example, that I won't be able to make Dragon scale/bone gear any more when I do this on Smithing?

Will my Sneak skill become completely useless until I level it back up again?

In a word YES everything will have to redone to increase back to 100% it allows you to increase overall Charachter level before making anything legendary though SO gather as many materials as possible to increase them faster especially Smithing, Enchanting and Alchemy and for abilities enchant a charm with the ability before making it legendary and wear it...

NS~

The only reason to make skills legendary is if you want to level your character by going through the skill progression again. Never understood why anyone would want to level their character that high as 99% of the game content is unlocked by level 50 and you only get to see a few new dragons at the higher levels up to 81.

As stated, if you smith, enchant, do alchemy I would gather as much materials and stock up, stock up, stock up, craft, craft, and craft. I would never reset a combat based skill.