Is multisite right for me?

I am building a site for a client and i’m trying to work out if I should use multi site or a lot of page templates to meet their needs.

Basic requirements:

One main site with 4 micro sites. The micro sites are linked to the main site but each has it’s own goals. The micro sites will each have different content and in the future will require additional functionality specific to them.

I also need a way to group each section together in the admin area as each micro site will have a lot of content/pages/posts specific to that site.

The plan:

The site will have a main parent theme where I can build the site wide headers,footers and functionality etc. I will then build 4 child themes acting as the micro sites where I can style and add additional functionality to each separate section. The header will have a main menu (home, about us, contact us) and a menu underneath with links to the 4 sections acting as micro sites (S1, S2, S3 ,S4). This will be consistent throughout.

The main home page will need to pull in the latest blog post from each microsite which doesn’t seem to be a problem and only has major data base query issues if you have a lot of sites under one install (from what I’ve read!)

Each microsite will have it’s own slider and content made up of multiple pages. In the future I will have to add specific functionality to each microsite by way of custom posts and need a way for this to be user friendly in the admin area.

I’m basically just after some advice as I’ve never used multisite. Should I :

A. Just use a single wordpress site with multiple custom posts and page templates to pull in all the data. (this could get messy!)

OR

B. Use multisite where I believe I can still interact with each microsite as a super admin, at the same time, having the ability to manage the micro sites content in a more professional manner. In the future I’ll be able to add functionality to a microsite specifically without clogging up the menu of others.

As far as I can see the only pain will be the menu system as unless there is a decent site wide option, i’ll have to create the menus in each child theme and use pages as the links if they were created in that section, and custom links to other pages on the other micro sites. Or am I wrong?

advice appreciated as I’ve never used it so not sure of the drawbacks or if i’m using it in the right way?