The only real downsides to SSD's are that they're far more expensive per gigabyte and if you delete a file, you actually delete it after the recycling bin (this can also be seen as a pro, however). SSD's also can last much longer without the risk of mechanical failures (I don't know if a SSD will survive a computer being fried, however).
Well I'm like to do last minute data recovery if I screw up... I kinda accidentally deleted my Blockland code archive I've been upkeeping since like 2005, and barely saved 70% of it maybe... I haven't been brave enough to assess the damage. Luckily it was a separate archive from the actual add-ons folder, so broken files I managed to overwrite with ones from the game... But I did modify some files and not apply the changes to the game, so that data is plain lost... Point being, I'd like data recovery to some extent if I screw up.
An external SSD? That is a huge waste of money. USB 2.0 doesn't come anywhere close to the max read and write speeds of a normal HDD, I don't think USB 3.0 does either.
I don't understand what does "rougher and wearing down" mean?
Verses my original harddrive, it makes noises which sound rougher. It's not as bad as the other two, which is why I use it. But it'll make noisily loud noises at time, and I can tell it isn't liking itself... Plus, when I run it, I hear like... hard to put to text but similar to: "dun... dun dun... dun... dun dun..."
And all this comparing to my old harddrive which has not been nearly as noisy in any activity.