vagueGM says:
What is our main opposition to doing this? Is it hard to get up there? Are we not allowed on the sabban walls? Can we talk/trick our way past guards or do we need to avoid them?
Ane has no plans —nor desire— to go through the sewers (yuck!)... but others might suggest it. Are we 'required' to use the sabban walls for some reason?
There is a fee to walk along the wall tops, collected by guards at the foot of the stairs. A few copper pieces, a nominal amount that gets you a brightly colored string tied round your wrist. Different colors for different days. Some people collect the strings, and some guards will smile at a rainbow wrist; others will cut off all the strings and collect a new fee.
Some people do use the sewers to move between sabbans, but for all the reasons you might think, it is not a preferred way for lawful folks.
There also are a few gates in the walls, but for each gate there is a fee, so if you are moving more than one sabban away it is cheaper to ascend to the walls.
There is no real risk associated with doing all this (at least the daylight routes), it's just a small expense that each of you can bear. Which route you choose will, however, impact what you might encounter. Wall top folks are generally hoitier than gate passers.