LTM Maintenance Page Lite
the benefits of using redirect is to be sure your logo file and css file are dedicated for the maintenance page.
imagine your application with /style.css file.
when you have no more active member, will the browser download this one or will it use the one from cache?
/maintenance folder may not be used on server side...
you also can have the same issue with maintenance page. which can be cached on client browser. with your irule, you have to manage client cache by adding cache-control header (and others) to be sure the maintenance page won't be cached.
another issue with your code is if server is unavailable generating the maintenance page, but the server goes up before style.css is requested... --> the style.css won't match the irule and the maintenance page won't display as expected...