Boo...
Everyone here is trying to help you adapt to the EV's capabilities and you are getting some good advice.

If, in the end, you feel it is not what you were expecting and is not workable, let me throw another possibility into the mix.

Replace the powered speakers with passive speakers and get a good 4 channel powered mixer. The entire set up would be less expensive, much lighter and give you all the capabilities you have expressed.

Ok... so you will have 3 pieces to carry (amp and 2 speakers, still lighter than the two powered speakers) plus conventional wiring, but you will also have total control over each individual aspect of your KB and voice.

When I was trying to make the same decisions as you, I opted for JBL 1500's (only 37 lbs each) and am using a Peavey 6 channel head...but 4 channels would do me just fine. The little 4 channel powered mixer is very light and durable and affordable.

Should you need a monitor other than the internal speakers in your keyboard, you can use your Sampson directly out of your passive speakers or monitor jack in the amp.

These suggestions are just something to stick in the back of your head should you decide the EV's are not workable for you.

Eddie