I can understand your concern, that being keeping a level playing field for as long as possible at launch. However it isn't possible. People progress at different paces, some have more free time than others. Having some players progress more than others over time is unavoidable, and because of this it's pointless restricting XP boosts. You're neither delaying or preventing the problem, it's just an inevitable trait of games which require time investment for progression. Also, please remember that advancing through the ranks grants access to more variety, not straight up power. People will learn the ropes before others arrive in EC and start playing, and will have more specialist equipment. We're told that beginners will have a strong foothold in terms of starting equipment (Apologies, can't remember source).
I've played a solid amount of APB over the years and it has an interesting payment model. The game itself is free and in theory you needn't spent a single cent/yen whilst competing with other players. That being said the amount of time and success you need to spend in game to earn the internal currency to constantly "hire" these guns and cars would mean you're playing the game almost exclusively. Option B is to hire the weaponry and guns from the micro-transaction marketplace (known as Armas). You can purchase items permanently (usually $10 - $15 for whatever you're aiming for) as well. The problem is that many of the most effective combinations of weapon and weapon-mod are found in Armas. The weaponry isn't necessarily "better" (I wouldn't call it Buy 2 Win), but it's certainly a hell of a lot easier to go down that path and not have to worry if you have enough in-game cash to purchase the weaponry you want for your next gaming session. I guess my hope is that Eternal Crusade sticks with it's currently listed model. From what I've read it seems to be a rather sensible system and one that won't put people off / make a gamers life more difficult that it needs to be (see APB).
If this game has anything like the microtransactions from APB (Make a gun OP on launch, nerf later.) I will be seriously pissed off and some of the guns from armas are just Pay 2 Win. Also. £25 for a PERMANENT GUN?
When i tested the APB:R BETA it was fun, we all waited to get permanent guns, then the first ones came, and a rifle called the "Joker Carbine" was at 60 dollars, its no joke.
APB:R Is the definition of pay to win. You're able to buy weapons and vehicles in the marketplace which are outright better than what you can acquire through regular gameplay. If you play free, enjoy the hundreds of hours of investment required for something that only has a slim chance of being nearly as good. A few friends and I in back in College decided to play and buy some of the most powerful weapons we could find in the store. It didn't matter who we were matched against, it was laughably unbalanced when 4 of us had the most powerful weapons in game (Destroying chasing vehicles in around 4 or 5 shots from each of us was insane). The payment model is ridiculous in APB:R. If you want a good weapon-rental system look at Blacklight Retribution. That game allows you to play perhaps 5 games and then your weapon is paid off. Anyway, I think we should stop talking about weapon rental. I don't think any race in 40K rents their weapons. You're given a weapon and you will die with that weapon in lore speak.