Their primary application is in targeting shielded and/or high-health units to take them out before the sniper bots can be destroyed. Sniper bots should typically be escorted with shields, direct-fire units, and anti-air units due to their fragility (obviously changing somewhat depending upon circumstance).
Due to their long range and accuracy, sniper bots can be very effective at sinking naval units attempting to bombard your base from offshore. Use them in place of Mobile Artillery when greater accuracy is required, such as when engaging small numbers of mobile targets. As they posses a higher DPS, but no Area of Effect when compared to T3 Mobile Artillery, but cost the same amount of mass, these should definitely be used when engaging enemy commanders or experimentals from range due to their much higher DPS and accuracy. The Aeon bot is better at generally damaging units due to its better dps and slightly less overkill. The seraphim is better at sniping high value units.
Alternative way to defend bases
Sniper bots are extremely good at taking out approaching units, especially Experimentals. If the approaching experimental is a Spiderbot, it will die within 20 seconds with 10 or more bots firing mixed with some T2 point defence.
If it's a Megalith, your bots will out range it by a great deal, especially if you are using Seraphim bots and whilst under heavy shields can make a player think twice about going forward with an army if you have 15 or more bots defending the front line. They can be rapid firing if not firing at the same time, making a very powerful army killer.
Factional Differences Edit
The Sprite Striker has slightly less health than the Seraphim counterpart. Its single fire mode falls between the two fire modes of the Usha-Ah, with higher DPS, longer range and lower ROF than the Usha'Ah's standard mode, and the opposite compared to its sniper mode. Use these in coordination with Shield Disruptors to neutralize enemy fleets with shields.
The Usha-Ah is unique in that it has two modes; one mode is close to a conventional direct-fire mode, and the other (non-default) is full-on sniper mode. Its standard mode is weaker than the Sprite Striker but fires faster, sniper mode is far stronger but very prone to Overkill. A bug (tested in 3606) allows you to get a free (meaning zero reload time) low-powered shot if you switch (back) to the low-powered mode right after firing a high-powered shot; the other way around also works, making the unit incredibly overpowered if you're inclined to exploit this. Also note that the range circle always indicates the high-powered-shot radius, even when the standard/low-powered mode is enabled.
The Usha-Ah is unique in that despite being considered a Bot, it appears to be some sort of hover unit, however it is not amphibious. Its propulsion system seems to be of some unknown origin.
Can they be used as an ACU killer? Edit
The answer is yes. However using these units as a snipe tool is very hard and impractical. There are much easier ways to snipe an ACU that are way cheaper and can be done at the the T2 stage. If you watch pros, you will never see them using this strategy. However, it is worth noting that inexperienced players are susceptible to this tactic. (THIS WILL ONLY WORK IF HAVE ACCESS TO CYBRAN AND AEON/SERAPHIM TECH. SERAPHIM IS THE PREFERED FACTION)
Quickly make it quickly to the T3 tech. Make sure you have enough mass income to support yourself. Build several sniper bots (preferably Seraphim due to their more powerful attack) and acquire a Cybran mobile stealth generator. Load the units on a transport (for better success, try to load up several transports or 1 UEF T3 transport)
If your opposing team has a dangerous air force, have you or your air player to send in a diversionary force and slip your transports by. Try to scout first so you can avoid buildings and static air defense.
STEP 3Try to land your sniperbots on a hill overlooking the opponents base or wherever the ACU is. If there are no nearby hills, land your sniperbots behind where the ACU is. Once they've landed, charge them up and send your transports in to locate exactly where the ACU is. if the bots are Seraphim, six should be enough to one shot the ACU (if there isn't a personal shield) it will take longer for the Aeon, but should be doable.