I don't think you will find any disadvantages but you will how ever need to play around with quiet a few of the settings to make it more pleasant for you it mainly personal preference stuff.

I would however activate the extra cross bars which is R2+L2 and L2+R2 which gives you and extra 16 moves with out having to change cross bars I found this a god send tbh I only really fill it with rarely used moves buffs or long CD's but it still makes room on your main cross bar.

I am healer mainly so I have all my heals and short CD's on my main crossbar and have dps and pets on the extra one works a treat for me