I don't think there are any functional or performance differences between these forms:

  [ -n "$var" ] || var=X
  [ -z "$var" ] && var=X
  if [ ! "$var" ]; then var=X; fi

It's a question of [your] style and taste, I think.

There are a lot more ANSI sequences that I could work into that block, but it is quite thorough for the space it occupies.

BONUS:

Here is my script to extract all of the stored WiFi networks and passwords when run as root:

  #!/bin/sh

  find /data \
      -name WifiConfigStore.xml \
      -print0 |
  xargs -0 awk '

    /"SSID/ { s = 1 }
    /PreShared/ { p = 1 }

    s || p {
      gsub(/[<][^>]+[>]/, "")
      sub(/^[&]quot;/, "")
      sub(/[&]quot;$/, "")
      gsub(/[&]quot;/, "\"")
      gsub(/[&]amp;/, "\\&")
      gsub(/[&]lt;/, "<")
      gsub(/[&]gt;/, ">")
    }

    s { s = 0; printf "%-32.32s ", $0 }
    p { p = 0; print }

  ' | sort -f