Selling 8GB buying 4GB?

Selling 8GB card buy 4GB ?

I got a 1070 and it’s gets around 24 MH/s. I could sell it for 350€ here in Germany and I have an offer for RX 470 Mining Edition 4GB cards for 150€. Should i sell my 1070 and get 2 RX 470 4GB cards or should I keep the 1070 ? I could buy 2 RX 470 for 300€. Is it worth it or nah? I’m still kinda new to mining…