The attached document written in Thai specifies a list of other documentation required before they will issue a back to back non-b so it is still possible to obtain them.
its generally very quick and efficient due to the appointment process, makes sure you have all the documents needed and you should have lots of time free
take your WP with you, on the multiple times I have been to Vientiane they kept it with my passport when I applied and gave it back the following day when they issued the visa.
I would recommend going to Kuala Lumpur as they are easier to deal with.