Anybody who thinks they know what would happen if Scotland left the UK, good or bad, is kidding themself. We have no evidence, just opinion and conjecture, nothing that we could accurately model. There’s no baseline to refer to with similar data from modern times based on other examples of a region seceding from a developed nation. Most longterm economic predictions are just guesswork and are little more accurate than a flip of a coun. If Scotland were to become independent tomorrow, we wouldn’t be able to begin to judge the success or failure for decades. Even then, you are comparing something that has happened with a hypothetical, an alternative history. You may have more data on how other countries have fared over the period but you’ll not be comparing like for like.
It’s the same with Brexit, we won’t begin to really know the long term macro impact for years when economic historians unpick the various strands, even then there will be a healthy amount of philosophising. People on either side will of course point to “evidence” that they were right but the whole thing is one big exercise in confirmation bias.
It’s better to come to terms with the fact that we don’t know what will happen, we can’t know, anything else is just opinion and rhetoric.
My opinion is that I would prefer to stay part of the UK. I am from England, albeit with Scottish, Welsh and Irish ancestry, but have a nice life up here with my Scottish wife and mongrel kids, I certainly don’t feel oppressed or disenfranchised (or living in a colony), even though my elective representatives in holyrood and London are not who I personally voted for. I’ve always felt British rather than England. My desire to remain is based on “better the devil you know” thinking. It could improve things, it could worsen things, things could bump along the same, I’d rather just not roll the dice.