So, what if I wanted just ONE H9? Can I buy the "standard" version and download the algorithms I purchased? 

Yes, you can.  All of the algorithms that you used to Max your H9 remain in your account, and if you buy a standard, you'll have them for your standard.

The question you asked was, "now I want TWO H9s again and have BOTH contain ALL the algorithms so what do I need to purchase".  That was the question I answered.  If you want ALL of the algorithms, you'll need to buy a Max again.  If you'd be happy just with the algorithms you already purchased to Maxout the H9 you sold, then you could just buy an H9 Core or H9 Standard.