Gosh, not pointing at anyone in particular, but I feel like I am beating my head against a wall on this...
The R-380 that is in the works is NOT any different dimensionally than an R-9. It is an R-9 frame and slide with a .380 barrel, mag and a different spring.
Why would you want one over a Seecamp? I don't know. Why would you want a Sig over an H&K? Just depends what you want, what you like, what you can get your hands on, and what you want to pay.
The R-380 is not a revolutionary gun that will set the market on fire -- its an evolutionary gun for people who want the R-9 package with less recoil, or for overseas sales where 9mm is not allowed.
Incidentally, is a Seecamp .380 blowback or locked breech?