As I've read through your suggestion. I'd see that 'Mob Stacking' is already a think that is implemented on the server. They do infact merge together, although it DOES have a capping point; this to my knowledge is 64, just previously boosted from 32. If you're proposing that they all medge together, without a capping point, then I'd agree with you on that. This would infact tear off the need for un-needed mob's, when they would just be easily allowed to be combined into one.
Secondly, the game: 'CoinFlips', mostly pertruded on another server as seen. I'd think this would be a game to enhance the concentration of people. Most people within the server would just like to have their alts seat at specific points, and for them to be left alone, 'afking' their possessions. This would be a great way to draw users attention, and create an active chat, along with active people to the server. In an addition of this, I'd love for a whole casino themed part introduced, with a multitude of different games that people can play on; in order for us not get bored of the same game. These of which can easily be mag-pied off other servers.
Thirdly, with the 'Sell Blocks', I'd say this is a bad idea. Sometimes, people like to secture off parts of their chests, in order to keep certain sellable valuables. For example, some people may collect 1/3 of their income of Emeralds, in order for them to be placed for /is level. Then, use the other 2/3 for them to sell. This would mean, for the people using this method now, to change their way of where they place the chests, this will propose frequent movement, to just get out of the 'range' of the sellable command. In another point of this, Zyrex has thought through this issue, and introduced the 'Sell Wand', this then comes with a sellable value on the store, along with the /shop on the server. You'll be able to select values into the chest, of which you can sell the whole chest of. You'll be able to go through large amounts of chests in just a few minutes -> possibly seconds. This then still allows you to be awake, and able to do so. If the command that you'd suggested was introduced, people could just afk, in that specific area, then have an auto-typer on a timer, then selling the values, maybe when they're busy; at work, or at school. This would break the current economy of the server, and make everything un-equal. Nethertheless, the server is a Semi-OP Skyblock, and having this would transfer it into an OP Skyblock, due to the ease of this.
On part of this, great suggestions. If you'd like to add any other comments, feel free to add. You may also message me on discord if you have any other questions.
Discord - pringles#6117