KEENWomen's Whisper Sandal

Hello i am a uk size 6 i have herd that keen sizing can be a little tricky. do i order a size 6 or a 5.5?

How do these compare to the Venice trekking sandals

Are these true to size? I’m a 5.5 but sometimes find I need to take a 6 with lengths coming in a little short on a closed toe

I have high arch and painful heel. researching for best sandals i came across this. yet, from the picture i can't see any arch support. is there any?