>but shaving with 4-blade cartridge designed for easy shaving is still 'miles' ahead compared to shaving with double-edged razor

What is/are the things you prefer with the cartridge? For me, I switched to the double edge a long time ago, and didn't really notice a whole lot of difference in what it does, but a big difference in price. I keep a cartridge for getting under my nose, but doesn't need to be replaced very often. For everything else I really don't notice a difference in shaving. I don't shave every day, so my razor tends to get clogged, and the double edged can be disassembled and cleaned in a couple of seconds while shaving. The cartridges can't really be cleaned out at all which leads to premature replacement and costing a lot more $$. Even when I did shave every day, I found I would try to suck every dime out of the cartridge, so I'd end up using a worse blade anyway.

I actually tried switching to a straight razor. Found it requires a lot more skill than I'm willing to put in to learning. But it appeals to me as the ultimate in reusability.