Best strategy to append to binary files

Actually E.toUint8Array seems to make a copy, just tried in emulator

>var h=E.toFlatString("Hello")
="Hello"
>var hb=E.toArrayBuffer(h)
=new Uint8Array([72, 101, 108, 108, 111]).buffer
>var hu=Uint8Array(hb)
=new Uint8Array([72, 101, 108, 108, 111])
>var hu2=E.toUint8Array(h)
=new Uint8Array([72, 101, 108, 108, 111])
>E.getAddressOf(hu,true)
=179852
>E.getAddressOf(hb,true)
=179852
>E.getAddressOf(h,true)
=179852
>E.getAddressOf(hu2,true)
=180006
>var hu3=E.toUint8Array(hb)
=new Uint8Array([72, 101, 108, 108, 111])
>E.getAddressOf(hu3,true)
=180300

So hu2 and hu3 made by E.toUint8Array makes new array from same buffer. Others work as expected.