You make some very valid points but, like others, tend to think people who vote out all have a strong fear of immigration. I don't blame you for this, the in camp have pushed it right from the start and at the moment it seems their only argument (if you want out you are racist).
I will be open with you and say I am voting out, nothing to do with immigration, I just don't like the way things are heading. We joined a "common Market" as a way to open up trading with other like minded countries, now we have a European government (what are they governing?). There is talk of a European armed force, if we have a problem like the Falkland's again will they fight for us or will we be left with no armed forces of our own to defend them? (Spain and Portugal could face similar problems).
I look at things like the British Steel industry (yep not owned by a British company but employing British labour) and wonder how much of their steel is bought in Europe, could they have helped more?
We are told we will lose trading rights with Europe (Switzerland and Norway seem to do ok), if we are lucky the Commonwealth will welcome us back (that's 153 trading partners not 28, and many of them are fast growing economy's).
We currently have a trading deficit with Europe, much of which is spent on cars. Do you think the Germans and French are going to stop selling Mercedes, BMW's, Citroens and Peugeots and hurt their own car industry? (the Italians do white goods and plastic industry machinery also)
We would be stepping into the unknown it is said, so what do we know about the future if we remain and will the remain people admit they knew it would happen if it all goes tits up?
The City of London will collapse, it is a world trade centre not a European one and has been for a very long time before the EU was formed, the fact that Germany want's to take that place will not change if we leave or remain.
I am rambling a bit now so will stop but could go on for pages but you get the gist