As an overgeneralisation, yes it is true that most C41 films are softer than (some) B&W films and chromes.

Practically nothing is less grainy than Acros or TMX, and nothing in ISO400 is as good as TMY2, so there's that. But then, nothing is coarser at a given ISO than Fomapan, so it depends which films you are comparing.

In my experience, Ektar is about as sharp and smooth as Velvia, maybe even better and RVP50 is the smoothest reversal film on the market, so the "best" C41 is smoother than the smoothest chrome. But then, the cheaper (Reala) and older (400VC) C41 films are very coarse compared to chromes of similar vintage (RDP, RXP), whereas the newer CN emulsions (New Portra in 160 and 400) are very fine. P400 is better than Reala and RXP but can't match RDP. P160 is probably as good as RDP.

So you can cut it whichever way you like really. Quantitative comparisons are also very difficult because MTF50 on the film means an entirely different thing on a negative as a positive because of the contrast gain in the printing process. A C41 neg that will achieve the same MTF50 in a print will have a lower MTF50 in the negative, which means comparing it to the MTF off a chrome is unreasonable. But then, chromes can have a higher Dmax, which means they naturally have the opportunity to get better acutance than any reflected print can achieve.

Just shoot what you like. If you want to try a colour neg that looks like a chrome, get some Ektar and print it optically. Hint: Ektar is comparatively cheap in 4x5"