In general, you would benefit more financially, and people would be more confident in buying VIP. In my opinion, VIP shouldn't cost more than 10 EUR. If you make it merely mandatory to play on the server, it should be accessible to everyone, and rich guys like me will find ways to spend 10k EUR on items. Currently, on Jade, I have one VIP account, and I switch characters to that account if I need to do quests in the Arena. There's no way 500 bons are worth a VIP on a farming character. But I would like to have one for a price of 10 EUR, not 30 EUR; it's too much on an old server. And if you go to VIP-only, VIP 9 has afk zen farmers, the rest is dead space.
In generally you should consider a-droping vip price to 10 EU which is totally logic or b-removing pay2win 10% stats from it. I get it it wont make any change in case where someone has +15 set and someone running in second wings but it would be more appealing for those who consider buying it but they see that they cant compete with someone who is owe geared and vip would not have any impact. Besides flat stats 10% increase strong makes stronger since they benefit much more 🙂