Hi!
I really need your help, I'm going to upgrade my actual size 355cc Motiva Ergonomic implant to a round Motiva 510 / 550 o 590 cc round implants called corse (High profile I guess)
Late to this one. But if you're still looking for info, I would discourage you from any of the teardrop (ergonomic) implants. A round implant will take on a teardrop shape when you stand up, and will take on a natural round shape when you lay down.
A teardrop/ergonomic implants will keep the teardrop shape when you lay down.
As for size? Look, if you're undecided on a difference of 40cc or 80cc, I urge you to measure 40cc (80cc) in a measuring cup. Next, pour that 40/80cc into a soup bowl and decide for yourself whether that difference will be noticeable.
While keeping an eye on the "look at how many CCs I have" prize is all well and good, you should be taking your goals to your surgeon, including pics of the women whose look you want. If you want to go huge, tell your surgeon to put as much in there as he thinks your chest will take. A good surgeon will do their best to find a balance between "max fill" and "keep the patient safe", as well as aesthetic considerations.
It sounds like you want to stay with a modest size, and that's fine. I would still steer you away from teardrop implants, though. I should add that one risk with teardrop implants is that if they shift, they will look odd and feel odd. I believe the only way to fix that is with a surgical revision.