It's OK for you to do this with your own squad composition. However, you should remember that most people aren't going to bother with an in-depth analysis of their helper squads. They'll have favorite allies they know they can rely on for certain performance parameters, but if they're looking at new helpers they'll look at total power first (which gives the edge to the tanky girls irrespective of their true strength), then speed and/or special abilities (Edelweiss, Lilac, Chocolate Cosmos, etc.). Some will look for multiple rainbows, which if they're maxed is about the same as total power anyway. None will go to the wiki to research whether a low-power girl's higher attack value will compensate for her lack of HP...they'll just assume that person just doesn't have any higher-power girls and possibly pick another helper.