Confused

I am excited about building a proper rocket stove but I am confused about something.
I like the look of the original batchbox design, it is very well tried and tested and undoubtedly works very well!
However I would like to build something with a big cook top like the one built by Fox James but his lovely looking stove uses a j tube style and you can’t see the fire like you can with a batchbox.
What I can’t get is why the riser has to be so high on some designs and hardly any height on others?

Can I build a 6’’ batchbox but with a shorter riser so I can put a cooking plate over the riser at a lower height?

I have seen the new designs double shoebox stoves but I can’t see how they work without a riser when the first design needs such a tall riser?
Sorry if I am missing something really basic but I would like to understand if someone can help me.

Hi Scott;
Peter developed the batchbox design. It uses a tall riser.
Matt Walker developed his riserless core. There is no riser in Matts stoves.
However Matts designs need a tall insulated chimney and utilize a bypass setup to heat the system so it draws well before switching it over to heat the whole stove.

The best way to build one. Is to buy the plans from Matt. They are step by step and when you buy Matts plans you get unlimited phone or internet time explaining any difficulties you are having.

Thanks Thomas, I guess I will have to do more studying before it all becomes clear!
Ps my names is John and I come from Scotland