Of the two the MSR definitely feels more consistent. If you want to practice in a public lobby then do it in FFA. You'll have more 1 v 1 encounters and you won't be a liability to a team if you're struggling with it. Be prepared for your KDR to take a bit of a nose dive too until you become more proficient.
That aside, if you want to do well with a sniper rifle in this game here's my advice. Do NOT run around with your sniper rifle like you think it's an SMG. It's not. Playing like that and trying to pop-shot everything will turn you into one of those universally reviled players who go 8 and 20. It's strength is for long range and ideally you want to be engaging enemies at mid to long range and from positions with plenty of cover to duck behind. (another tip; if you aren't already playing on tactical then make the switch). If someone gets too close and you've no time to switch to a secondary, that's the time for a pop-shot, but for the most part you'll be looking to dragscope. Remember if you have the time always use it to be sure of your shot and guarantee the kill.
I got a lot of good tips from a guy on YouTube called BTR SlowBurn who has a series called "Snipe like me", which is very useful and really helped my sniping game.
As for 360s... in my opinion, there's nothing cool about them. They are entirely dependent on luck and you should avoid doing that sort of thing in a public match. If you want to get some friends in a private lobby and jump about doing that then go for it, but the only people I've ever seen attempt that in a pub have all ended up dead in mid air. Remember, if you're on a team the aim is to support your team for the win, not try and get some "cool" clips for a montage.