I was recently playing the most excellent TTW version 2.9.4 on Hard difficulty with Hardcore mode, my character was around level 10 or so, wore Armored Vault 101 Suit and was able to defeat my first 3 Talon Mercs encountered near Super Duper Mart with Spiked Knuckles (upgraded with some TTW WMX mods) - My character got hurt pretty bad (barely survived), but thats what you get for bringing knuckle dusters into a gunfight. Basically, I closed in as fast as I could in order to avoid getting frag grenaded and I used several VATS attacks and these knocked their guns to the ground, after which it was possible to simply whittle them down with lots of punches, stopping every now and then to activate a new stimpack which heal over time in hardcore mode (used up something like half a dozen in the fight).
Now, this first batch of Talon Mercs was by far the toughest challenge I faced around level 10 in this playthrough; After that first Talon encounter, I simply wore their superior armor and used their own weapons against them. My second Talon Merc encounter (My character was level or a few higher than the first) was outside the Northwest Seneca Metro Station, I ran away from them and dropped a couple of Satchel Charges to soften them up a bit, then I took cover behind corner of a building and finished them off from close range with a Sniper Rifle my character was not even strong enough to properly use (Strength 3 vs Sniper rifle req 6).
Talon Mercs being tough opponents is not any kind of design flaw or a bug in my opinion, it's a feature - I like the extra challenge, the very real threat they pose to any beginning wasteland hero wannabe. (I also never nerf the super mutants either, I leave the TTW supermutant rebalance option off.)
However, I have to admit, that game balance-wise the Reinforced (and Mk2) Talon Combat Armors they wear in TTW are relatively much tougher armors than what Talon Mercs wore in vanilla F3. OTOH it is also worth considering that IIRC Reilly's Rangers Battle Armor is supposed to be the very best Combat Armor in the Capital Wasteland region lore-wise, but it offers obviously inferior protection (DT:17) when compared to Talon Combat Armor Reinforced Mk2 (DT:20). Perhaps bumping up the Reilly's Rangers Battle Armor DT to 20 or so might be a good idea, I dunno?
In TTW, the Talon Combat Armor is only DT:13 when compared to regular Combat Armor DT:15. Perhaps it would be even better idea to reduce Talon Reinforced and Mk2 by similar amount (DT -2) from their regular combat armor equivalents (Talon Reinf would become DT:15 and Talon Reinf Mk2 would be DT:18)?