My beef with the skirmisher is that it really just comes too late for its strength.
The game already has a 30/17 str, 3 move range unit - the pitati- that comes at archery and costs 70 and has two range. Now, not a lot of people would skip the xbow upgrade and sacrifice the range. They just wouldn't. So this regular skirm- probably not a battlefield bruiser.
What they did was they took the scout - a 10 strength unit- applied the +10str /era formula, came out the 30, made it a ranged unit. Ranged units feature a melee strength 10 below their attack strength. The only exception t this rule is the ranger, which is 60/45. but I'm guessing they didn't want it compete with field cannons. (They dont- they only have one range!) (note: siege units are not ranged units but even they sorta follow this)
The skirm would be very interesting as an early medieval unit at 35/30, though. A speedy and weak xbow!
The Warak is going to be a terror if you can barb hunt and do some limited warring with it.
With Warak`aq's double attack, they'll be able to take full advantage of Survey to get promotions very quickly. Upon reaching ambush (for an additional +20 combat str.), these UUs will become absolute monsters in combat vs. any unit within their era.
A group of tier 2 warak (easy enough with survey)+ the terracotta army (grants a free promo to all land units) give you the ambushers you need to run through everything including knights. (Construction is the tech before machinery, so you can probably make this work. The AI doesn't always prioritize this wonder.)
Then you can upgrade them in industrial to
80/65 Rangers (albeit no double attack) which makes them stronger than any non-UU industrial unit
even in melee, including the new cuirassier. The only reason this even makes sense is because waraks actually hit really really hard so they can fight regular troops to seize the extra promotion or two to ambush.
Later on, of course, you see the industrial corps and modern era armies, plus the atomic spec ops. So you can take this same core of ambush warak and eventually land yourself some
102/97 spec ops armies that run through any terrain and paradrop and can snipe support units. A mech inf army does 102 melee, for reference.
It's too bad survey obsoletes at exploration. They really need to add some recon line cards- maybe an earlier update to survey that grants the experience and a double production, or maybe roll discipline in and grant them a combat boost vs barbs.