Native comments or FastComments?

I’m in the final stages of moving my WP blog to Ghost. The only thing remaining to factor in is the commenting system. I’ve dabbled with the native commenting system and for basic functionality it seems fine. I don’t have it working on a live site so have no idea about the volume of spam that gets through …

However, I’ve also looked at FastComments which has better formatting (including Markdown), the ability to embed graphics, upvote comments etc. These are more likely to be useful to me when replying to comments as my readership is generally non-techie. Routinely posts to my website now generate 20-40 comments.

The advantage of FastComments is the ability to import my 7000+ WP comments ‘natively’ rather than just add them statically (as another block of HTML) to the bottom of the imported posts.

However, the reality is that older posts tend to generate few comments - and even fewer replies to comments - and so perhaps I’m adding costs and problems for myself rather than simply using the native commenting system.

Has anyone faced the same choice and are there any compelling reasons for or against either of these options?

Thanks in advance.