The Xenoswarm isn't any faster.
Battlesuit (assuming tectonic scanner)
Genetics, Genetic mapping, Physics*,Bionics**, [free tech servo machinery](and a quest)
*less expensive than Robotics and Alien sciences
**Just as expensive as tactical robotics/Alien Ecology
Don't you still need Engineering to "mine" Titanium? I thought Tectonic Scanner only allowed you to see these resources and not make use of them. If you can't mine Titanium before you get Engineering, then that's another tech Battlesuits require.
Also, you have to take the time to build an Institute and then wait for the Institute quest to pop before getting free Servo Mach.
Lastly, Xenoswarms are technically faster to produce. Every 3 Battlesuits (160 production each) you produce is 4 Xenoswarms (120 production each) the other player can produce.