Adele Hi,
You definitely want a tip that conforms to the C curve of the natural nail.
Velocity does have a deep curve, but eclipse is the one I use for those high arches where the sides go almost vertical before arching over the top of the C.
I didn't use Eclipse all the time, but only for the nail I describe. I found it 'hugged' the sides of the nail beautifully. I used to keep a box in my desk just for when the occasion arose. If you havent tried them a 100 box is handy to have. One type of tip just won't fit everyone which is why we have choices.
Of course you can always sculpt them ...
By the way, the saddle technique is useful for fan nails, bitten nails, higfh arched nails, missshapes ... whenever you want to get that sleek look when you wouldn't get it otherwise.