i read the post so i thought i would give some insight into the matter since I have done a lot of research
First of all - switching from vB to another system will be tiring for the administrators since it will involve converting the database to another format, this is usually done automatically by scripts written by the board sites like IPB, SMF, vB or others.
Current 'top board systems' are:
Pros: Good coding causing less queries to be generated thus less load on the server, plus its coding is probably the most compatible with other systems.
Cons: vB Charges $160 for its software plus $30 annually for license upgrades, wheras other board systems nearly as good as this one are completely free.
Simple Machines Forums (SMF)
Pros: Completely free, very fast and customizable plus very high level of security.
Cons: None known of so far
Pros: Fast and reliable coding
Cons: Costs money to buy not free - not very user friendly
Pros: Completely free and probably the most powerful with regards to mods and addons available
Cons: Not very fast and coding is a little tiring for servers
Apart from these there are other boards available as well which I dont know too much about
myBB (clone of vB - completely free)
The pros and cons expressed in this post are based on my personal inference of the boards and my knowledge on them through reading different articles.
My Opinion: Islamic Board should stay with vB if they feel the cost is justified otherwise if they want to save money they should switch over to SMF which is excellent and free.
Board I use on my site: SMF