My own experience (sameple size of one) tells me that the greatest advantage to a classic double edged razor is in learning the technique. You WILL cut your face when you first start with it, but if you persist, you learn the right amount of pressure, the right stroke length for your face, the right angle, how to clean it, etc. The handle on my double edged razor broke, and I couldn't be bothered to replace it (lifetime warranty though). For about 6 months now I've been using cheap double blade dispoasble razors (and only replacing them about once a month) and I'm having a hard time convincing myself to go back. I used to swear by the badger hair brush, nice shaving cream and Merkur blades, but now I just use the hot water in the shower and a cheap plastic razor (that is rarely super sharp because it's usually weeks old) and my shave is just as close. I reckon I could dry shave if required, but the burn would be unbearable.

Yes, with a minimal investment in a good brush and Merkur razor + blades a couple years ago, I've already saved by going the double-edged way plus the shave is way better.

Only real problem is that I still haven't figured out how to do carry-on only and keep blades on me.

I've only ever had one TSA agent realize that I didn't have a cartridge razor in my dopp and confiscate my blades. Since that happened (but before I became an enormous beardo), I've brought only the bare minimum blades needed for my trips packed edge on to the x-ray scanner and left the butterfly in my shave kit but opened to show it was empty.

I imagine a safer and less obstreperous way might be to just buy an injector razor for when you travel.

I use Harry's for the TSA and DE Safety for day to do. And because I only travel once every 6 weeks, I am okay with it.

I usually disassemble my Merkur before it's in my toiletry, but have a spare blade or two in wax paper floating around-- it doesn't seem to attract attention if it's not inside the razor assembly...