Oh my god, I'm finding the game so much more rewarding on survival mode.
I was afraid that everyone and everything would be pretty much bulletproof, but I'm finding that really isn't the case. I was frustrated with the lack of legendary item drops, so I dialed up the difficulty in certain situations. I eventually forgot I had it on survival.
It's more challenging to be sure: the enemy encounters seem just a little more frequent, and there's often a legendary enemy among them, but with good sense it's all manageable. As Strong would say, it's "LESS FIDDLING! MORE FIGHT!"
And the legendary items are dropping regularly.,.. seems like about 3/4 of the legendarys drop a legendary item. Those encounters in normal mode where there's only 3 enemies that had gotten so easy now have 3-5 to fight, often with a legendary among them. The 'hotspots' that always seem to have a fight going on regularly offer a farmable legendary enemy (for me- particularly the one 'worst apartment building in the world' just down the block from Diamond City where DC Security is always fighting SuperMutants - the one you hear all the gunfire from every time you leave the stadium.) Very few item drops are worth a dam at my level IMO, but I've gotten a few pieces of incredibly useful gear @ lvl 35 or so.
The health regenerating so slowly is the worst thing about it for me, but if you invest a perk or 2 in 'Medic' and use quicksave wisely, it's doable.
Don't be afraid to try it.