MIL & MOA... like measuring distance in meters & yards... they'll both do the job
I would DEFINITELY not change scopes for mil/moa change over. If your current scope works, stick with it and just shoot for fun and practice.
If choosing between the two, go MIL for sure. Razor Gen 2 is a great scope, used they are still under warranty.
Even at the top level, you're not making $$$ really. Just bragging rights. Spending a LOT of time and money to be competitive is not realistic or smart for the average wage earner.
Honestly, if your scope works for you, just stick with it and just practice, know your drops (verified to what you ballistic app tells you), and focus on reading wind by shooting at different locations.
Vortex does indeed have a great warranty and my favorite scope is a RG2, but I really like nicer scopes. It's worth $2-3k for me to have great glass to look through. Doesn't apply to everyone. If your scope works for you, you have to ask if it's what you want and need... or what you think you need because others have it.
If your scope is working fine (tracks decently), just focus on your skills and ENJOY shooting and learning more about becoming a better shooter. If you haven't tried it yet, for $18 look for the upgrade pulldown at the top two to the right of "forums" and get the training for a month. Lots to learn.
If you want to buy once cry once, AND you'll have enough $$ left over to keep shooting regularly without breaking the bank, then get the scope and sell your current one.
But between ammo/shooting and new gear always go shooting.
Like owning a sports car and debating whether to put in a new turbo, but can't afford the gas and tires to actually drive it.
Have fun!