Having played in bands for many years, my experience is that the band will stay together longer if all the players have the opportunity to shine but you have only one lead player (or one lead vocalist and one lead instrumentalist). A group can have only one vocal flower (and/or one instrumental flower) but needs side players (the gardeners) to nourish the flower(s). One flower and two gardeners works best = trio. (Stan Rogers touring band had guitar, bass, fiddle/flute and three vocals) It is usually best for the longevity of the band that they all be of the same gender & persuasion. You often end up sleeping in small spaces, the van, one room, somebody's sink, etc. Several guys and a lesser number of women (or vice versa) on the road for any length of time tends to lead to hanky panky - then a big bust-up, then you've either lost a band member or there's a real tense situation happening, either one of which is the death-knell of the band. The rest of you have to decide who gets kicked out and now it's a lot of work to bring someone new on board with the existing cliques that person has to merge into. My recommendation: 1)Decide what it is you want to play 2) Figure out the minimum number of people it will take to accomplish the sound you want to achieve. Choose the best musicians you know and know their good and bad points, both musically and in personality. 3) Work with the minimum number of people - If some piece sounds weak or needs more help, decide if it needs to be in your repertoire. 4) Find out of you have enough good material to play a concert (90 minutes) and that you are happy with the sound of EVERY piece with your current line-up. 5) Only after exhausting 2,3 and 4, consider adding another member.