Personally, I feel like the reason they're not more widely used is familiarly and upfront cost--familiarly being the biggest (seeing you mentioned being scared)

Personally, I feel like the reason they're not more widely used is familiarly and upfront cost--familiarly being the biggest (seeing you mentioned being scared). Practice wise, they really seem on par with cartridge, IMHO. I don't feel like I have any fancier technique or am especially careful when using it. I really use it like a would a cartridge. Changing blades means loosening a nut instead of popping off the blade--but I much prefer having 100+ cheap spares so I don't give a second thought to swapping for a sharp blade compared to only having a dozen cartridges onhand (because I lament spending $25) and having to remember to buy more. The only clear downside is flying (in which case, use cartridges when on the road until TSA lightens up).