I have had a little more time to play with the twentynineteen theme. I'm still not convinced by the new 'blocks' based layout at this stage. Whilst I get the idea of being able to move the content blocks around when putting a page together the features I want are not yet there.
I have sections of content on this site that I have styled to look like a command line for use when posting command strings. I would like to be able to create a block with that style from within the editor and reuse it. Currently I can only save a section of html and any changes to it will affect all of the other blocks of that type.
I can think of a way around the issue but it isn't that practical. After a little research I discover that I can probably create my own custom blocks or use a plug-in to do so.
This is inconvenient as I either have to trust a plugin going forward and hope that it is maintained or spend the time learning how to make my own blocks. Neither of these options are that desirable.