a bit taken aback at having to defend the case for a smaller country against a larger one
Such a massive step should be argued not just in relation to UK or not UK.
Scotland has done extremely well as part of the UK. We're less stifled as part of a bigger, older country than as a little new country.
You asked me to explain why Scotland is not significantly different from rUK and why this matters. It matters because we're part of the same (small) island. And we have the same language, long history, culture, religions, climate, institutions etc. Therefore there has to be a very strong reason to put a border across the middle of that island. If there were differences it would be understandable, but there aren't.
Anyone happy to break up the long established union as a result of narrow majority vote in a referendum should be prepared to explain their position in detail with as much evidence as possible and very strong justification which relies on more than just the opinion that they think we'll be better off.
I realise that this is the case with the EU referendum too, but the hideous mismanagement of that is not enough reason to take Scotland out of UK against the will of almost half its population.
The SNP candidate for my constituency was at my door this evening. According to him, this election is "about Brexit". The conservative party certainly agrees with him. Not for me it's not. He tried to explain why it should be about Brexit for me by detailing the very adverse affects of TM negotiating a deal with USA which would allow USA meat to be sold here with the lower USA welfare standards making Scottish meat uncompetitive. But this would apply across the UK. Unlike him I care about everyone in the UK. He thought I might have agricultural connections because of my accent so was trying to appeal to my (selfish) interests. He said it was heartbreaking to think of England under a cruel conservative government but is facilitating this by splitting the anti-conservative vote and is happy to leave the rest of the UK to its own misery apparently.
No independence campaigner should be taken aback at having to defend of justify wanting to break the UK into smaller countries.