If you're used to games with lag compensation on weapons, then yes, JA's old school Q3 networking can take some getting used to.
If the MB2 devs felt so motivated, I'm fairly sure they could incorporate
the unlagged Q3 mod into JA/MB2.
However, it'd significantly effect class balance; gunner classes, and instant hit weapons in particular, would become easier to use.
It'd also introduce all the nasty artifacts* inherent with backwards reconciliation latency compensation.
*high latency players being able to shoot you 'in the past', long after you're in cover/around a corner.
A minor improvement can be achieved in JA/MB2 with the console command "cl_timenudge -X" where 0<=X<yourPing.
It works by forcing your client to predict Xms into the future, thereby mitigating the latency of your inputs.
However it has side-effects; most noticeably other players will appear to warp when they change direction.
It's worth mentioning that while Q3/JA/MB2's networking is 'old school', it isn't inherently worse than more modern engines.
While it doesn't do a very good job of hiding latency (and thus isn't noob friendly), it is very predictable, learnable, consistent, and efficient (very low latency), so has a higher skill ceiling.
All that said, projectile speed is a completely different issue, and not particularly relevant when comparing MB2 & SW:BF.
