Is it worth making a mining rig now ?

hey all , I have just started mining like a week ago and have only just managed to get it working and love doing this. But i want to make a better rig with more gpu's And saw that the stly of mining is changing to pos i think it was witch means you dont need GPU's to mine . Is it worth making a new rig now ? or just stick with what ive got 2 x r9 280x at 40 MH/s ??

thanks
sorry if it didnt make much sense
ben