I thought the Jetpack machine gun is about as powerful as the SMG, but I need to check again. He has an advantage if shooting from higher ground (More chance of headshot).
Custom game will be patched in according to GG forum/blog post.
I don't think the Marksman makes a lot of difference in objective games, at least not in my games so far. First, I'd like to correct my mistakes. A few times, I thought I saw a group of hidden enemies, but in reality, I was in a captured TSP
lol
. So those enemies were spawned right there -- (no) thanks to the Tacticians.
The Infiltrator is hands down the best Search and Retrieve champion. So far I believe the Engineer, Tacticians and Medic make the most differences in objective games in general. When attacking, the TSPs make a strategic difference (e.g., In Salamun Market, they are right outside the Search and Destroy objectives). There is also one or two ammo crates near the objectives. Once those resources are captured or repaired, it is a significant advantage no Marksman can undo. I can spam grenades 3 at a time to soften the compound before charging in. High level Tacticians and Infiltrators can also spam rockets. Once in the objective room, I would spray everywhere to identify any Marksman, while my teammate(s) behind me take the objectives. If I were taken down, I'll have a second chance to attack enemies from behind (or while they were disarming our charges).
So far, the most annoying Marksman are best in locking down certain routes. e.g., straight down the corridor, near spawn points; but it's usually a temporary advantage (Good for delaying enemies, like Infiltrator camp raping the spawn point). But you have the Exo, Jetpack and WASP to wipe them off the battlefield in some maps. Marksman is also handy at sniping people off the noisy WASP. ^_^
EDIT: In general, the Infiltrator's perfect disguise also doesn't amount to a solid win. We bullet check every man coming into the objectives. Once they are exposed, the Engineer's turret should be activated. Infiltrators are most useful for sprint speed, and may be in hectic situations where we can't check every man.