I have only recently been able to shave atg, and my neck has always been my hardest area to shave properly. What you are saying sounds somewhat normal in my opinion. I would suggest trying more wtg passes and taking a little more time with it.
Using a safety razor or straight blade takes a bit more time and patience than using a cartridge razor. And that being said, don't feel locked into it, if you feel that shaving isn't the hobby for you and you are adequately happy with a m3 or the like, then by all means go with what makes you happy
. But I do think that a little more time and patience would make you happy with your DE.