@karlos103 Judging by your posts so far, you seem to have developed a classic case of 'upgrade-itus'.
It's a terrible affliction, most contagious within the Airsoft community with a 75% infection rate between players (you need 'X' for that gun, mate!), an 85% rate within Airsoft shops (let me sell you this shiny thing - it'll double your range!), and most horribly, a 99.95% rate within the Tokyo Marui owners community (because TM is perfection out the box! Just needs a few upgrades...!) .
Symptoms include wanting to 'upgrading' their gun without shooting it, spending more than the value of the gun in their quest to make it shoot amazeballs, a penchant to tell everyone how their 'upgrades' are the bestest and telling all others should be fitting the same to their guns.
Infection long term generally ends with various degrees of disappointment (75% of cases), frustration (90% of cases), a drained bank balance (100% of cases) and questioning whether it was all worth it in the end to shoot tiny plastic balls at each other (80%).
A very small number cases (<5%) report that the player reaches a type of 'Airsoft Nirvana', whereby all their guns work beautifully, reliably and the player moves past the need to acquire anything further. No one within the TM-owning community has been identified as reaching this state ...?
Jokes aside:
Cracking open gearboxes, replacing electronics, new barrels and hop units - upgrading everything without a frame of reference (i.e. playing experience with your gun in 'stock' configuration) could very well lead to disaster. Many upgrades could be described at best as 'side-grades', and there are a number that can be detrimental to performance. You won't know this if you've replaced a sizeable chunk of the stock parts on your gun without using it for a good few playing days first.
Go out and play a couple games with what you have already - see how it works, where it falls short compared to other players, and what you want to improve. Upgrade ONE THING at a time, test it thoroughly at your next game day, and see if it actually improves anything.
Oh, and circling back to your original question, G&G hop units (both dial and rotary) work just fine.
No need to replace until broken. But we all know you'll want to replace it anyway.