This would be a love/hate situation for most people. Personally, the rewards from pickaxe level up AND pickaxe perks are fine with me at the moment. Allow me to explain into further details as to why I think this.
Newly made pickaxes can level-up faster, allowing for rewards faster. This allows new players to climb there way up at a faster rate. In this new season, the prison rank-ups are a tad more expensive than they were last season (correct me if I'm wrong). Its still a grind to get there when you start out brand new so unless you start with a god pickaxe, it's balanced. Rewards stay the same grinding as you climb through the ranks, making it harder and consuming more time to get to the next; prestiges included. This is ideal for any prison server.
Now in my opinion, there are many cons to this change that you are suggesting can be quite broken. This goes for people who are grinding prison a lot, like myself. As a player who has everything on a pickaxe maxed, it still takes time to get money in-game. If these changes were implemented, I would be gaining in-game money at an astronomical rate, instantly breaking the current prison economy. I would be making way more money in the AM overnight than I would be mining at the current update. As much as more money sounds great, all its going to do is make IRLs more expensive, and pmines cost a lot more. Unfortunately, the only couple of "Pros" I see in this scenario is new players getting to the "Angel" rank faster and veteran players prestiging faster.
However, I am not a staff member and this is not an official response to your suggestion. I am simply giving my two cents on the subject. The changes you would be suggesting may or may not be added. Good luck on the server!
Very respectfully,
-MrWangGang
