Given the explanation why your function fails in the above post, here are soemwhat awkward workarounds which would either won't show the unit at the end at alll or would require you to know the unit of the result and place the correct inverse function ("unit") there.
I won't advise using Prime but this is sure an advantage of that version that it is able to display complex numbers in polar representation out of the box. But then you won't be able to hide keywords or display symbolic eval and assignment sign as ordinary equal signs.
