Economics - it is impossible to say how the experiment will work out until we conduct it. No-one can be an expert on a system so large and with so many variables that cannot be quantified. There are credible arguments that go both ways on this.
Loss Of Sovereignty in trade deals - you'll need to define what you mean by sovereignty. To me it is a legal term, Whose court has the last say? If we had a trade deal with the USA would the U.S Supreme Court have the last say in matters of English Law? No it wouldn't. As a member of the EU a UK Court does not have the last say. I find that unacceptable.
Labour shortage due to Lower Immigration - the point here is that you do not necessarily have lower immigration you just have control over who you allow to immigrate. If you need doctors and nurses or whatever , they can immigrate. You don't want unskilled labourers because you have enough of them unemployed here already, so you don't let them immigrate.
Current Lash Up:
TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.