Hi Lewis
Like you, I persevered with toe clips for most of my cycling life, undertaking several major tours, and retained toe clips even when I bought my RST last year! Finally a couple of months ago, I took the plunge with SPDs and my conclusion is that there's no contest: SPDs are much more efficient. As for getting out of them, I've not really found it problem as long as I'm anticipating coming to a standstill: possibly being relaxed as you come to halt so that you remember the right movement probably makes a difference. If you are tense, its probably a bit of an impediment to releasing your feet smoothly.
I have fallen off once, at the end of a long ride, in Brixton, as a bloke in nothing but underpants holding a pint of beer started dancing in the street directly at the point where I was due to stop in front of some traffic lights. My tired confused brain forgot that I had SPDs as I came to a premature halt, and much to the amusement of onlookers, I duly keeled over!