Used both a lot in my renovation. I'd never go without pistol again.
A) it helps control the amount way better B) you can just shut it off and use the rest later on without bothering with sealing it airtight. C) better handling and weight distribution
The pistol addresses your main concern. The can stays on the pistol and is good to go even for weeks.
And the cleaning part doesn't matter to be honest. I spent a few bugs on the cleaning spray (basically alcohol/acetone solution as you've guessed) which can be easily sprayed. After use I spray a bit into the opening of the pistol.
I like to have it available in case I fuck something up or want to protect a surface, would even spend the money without the pistol.
The pistol costed like 15 Euro and saved me several hours by now.
The cleaning spray I would get even without a pistol just because it's so handy to quickly dissolve foam.