Happily, I can report that I have never had to extricate myself from a crashed plane, so I don't speak from first hand real situation training. I have assisted three people (in two different crashes) though, who have required inverted extrication. One was fatal, so a different situation, he could not help himself.
Yes, there may be a bit of a fall involved, but GA cockpits aren't large, so it's not far. It is important to note as you latch the seat belt, how it will unlatch. I have flown a 1977 C182 a few times recently, whose original factory seatbelt installation (I recognize it) has never been corrected, such that the shoulder harness keyway clips over the pin on the lap belt, but its on the wrong side. SO when you unlatch the lap belt, you're still secured by the shoulder harness, and unlatching it will not be possible until the weigh is removed from it - a very unsafe condition. I have told the owner twice now to have it changed. It's actually a certification requirement that it not be this way. I've encountered a few others ove the years like this. Some can simply have the lap belt halves exchanged side to side, but this does not work for all. If in doubt, carry a webbing cutter, easily available in auto stores.
I have taken the underwater egress course, which is an excellent opportunity to practice this inverted immersed, and blacked out. Happy, "falling" out of the seat is not so much a problem underwater, so you can focus on all of the other challenges!
Canopy aircraft present their own challenges. If the aircraft is certified, there will be a procedure. When I flew DA-42's I familiarized myself with the procedure which is for the back door, it can be unpinned, and [hopefully] pushed out of the way. Other non certified canopy types I have flown (Thorpe T-18 and RV-4) had canopy arches designed to hold the aircraft weight (a roll bar), though I admit that on those long ago occasions, I did not familiarize myself with how to actually open the canopy inverted on the ground.
It is important to know that when a cockpit is inverted, it will be very disorienting. I have swum in the cockpits of inverted Cessna floatplanes during recovery, and it is very disorienting, when all the features you're so used to are in the wrong place. When I went to the aid of the two pilots who flipped their C 170B on the runway in front of me, after assuring that they were not hurt, I asked them to confirm that the master and fuel were turned off. The more senior instructor of the two searched the ceiling of the plane, which was now on the ground, for the fuel selector. I reminded him that it was now above him, between the seats. He still had trouble finding it.
It's very wise to have a plan to get out of whatever you fly, in all situations....