Sorry if I am wrong with my assumptions, I have read through this post and gotten all the info I could.
1. I feel as though there should be enough grinding in the leveling system that players feel specialised and unique with their skill setup, however I don't want older players to be miles ahead of newer players. They should be able to catch up after putting some work in, but not having to grind for months.
2. I like the slayer level dictating what weapons you can use against mobs, but against players it may make you seriously gimped if you want to protect yourself from PKers who are all decked out in shiny armour.
3. Like eve online I would like the choice to pursue any option without being gimped in another. If i put the work in, then i would like to be able to use diamond weapons/armour and still go mining with a diamond pick. Rather than having to choose a set path to take. For example you may have a combat class as a primary and then choose a secondary crafting profession.
4. Rather than having the best tools at your disposal at the end of your leveling. Have them earlier on but give additional bonuses for a higher level. For example the previous mining levels gave a chance for extra ore, this would be worth a large on going grind for after you have gained the ability to use diamond picks.