I think the main topic here is 'what's in it for me?' as a subscriber and do I need to change anything from what I'm currently doing?

The main idea I see here is - pay for your subscription (premium content) using rewards you earn from your comments (which is the main channel I see your users earning their rewards).

And this is when I imagine they look nto signing up with STEEM.

This is the section I mainly focused on:

How are Rewards Given?

Rewards are given by way of upvotes on the posts and the comments.

I suggest to remove the word posts and just retain the comments. Posts can come later when they experience getting rewards from their comments.

The value of an upvote depends on how much the voter has vested in STEEM. The more they have vested, the higher their vote worth

I think providing this information is too much at an early stage (when they're just signing up). This can come later. For me, it's enough to read this for me to sign-up:

The Excel Club will be rewarding comments on our blog posts with upvotes.

For this one below, I'll just remove it. If they like what you post, they'll intuitively upvote your posts. Or you can ask them to upvote your posts once they've signed up.

Likewise, you can reward The Excel Club blog post with upvotes too. If your vote has any value, you will get up to 25% back in curation rewards.