Like I said, dexterity speeds up everything (except idle). This includes reloading as well. Time it yourself if you don't believe me (or check the source code). Take, for example, an Arquebus attack cycle. With no attack speed bonuses/penalties and dexterity at 10, this will have an idle time of about 0.2s, 1.5s attack animation, 2.5s recovery, and about 6.4-6.8s reload time for a total duration of around 10.8s. Set dexterity to 20 (30% speed-up), and the duration drops to about 10.6/1.3 + 0.2 = 8.4s. If it did not reduce the reload time, that would be considerably higher, at about 4/1.3 + 6.6 + 0.2 = 9.9s.
I have already timed it- I found similar results, but the reload animation in particular did not change.
Then you should time it again, because it does. Timing 5 consecutive Arquebus attacks I get an average duration per attack of 10.7 for DEX=10, 8.3 for DEX=20 and 6.9 for DEX=30. Assuming an idle time of 0.2s (thus yielding 10.5, 8.1 and 6.7), this fits very neatly into the duration you would expect if DEX scaled everything: 10.5/1.3 = 8.1s, 10.5/1.6 = 6.6s. If only attack and recovery scaled with DEX, it would be virtually impossible to get anywhere near 6.9 seconds, the attack + recovery would have to be reduced to almost 0 for that to happen.
But more definitive still is the source code. In the AI.Achievement.ReloadWeapon.OnEnter() function that is called when reloading is initialized (or continued after interruption), we have the following bit of code:
float num = 1f;
if (this.m_firearm != null)
num = this.m_firearm.CalculateAttackSpeed();
this.m_speedMultiplier = component.ReloadSpeedMultiplier * num;
The ReloadSpeedMultiplier reflects stuff like Gunner. The CalculateAttackSpeed() function grabs the Dexterity attack speed multiplier (as well as any speed-affecting AbilityMods if the attack is part of an ability being used, not sure this is ever used in practice). Dexterity and Reload Speed bonuses are thus multiplicatively combined in this speedMultiplier. In the same function the reloadTime is set to however much time was previously spent reloading (if any).
In the AI.Achievement.ReloadWeapon.Update() function we have:
this.m_reloadTime += Time.deltaTime * this.m_speedMultiplier;
The reloadTime is thus increased by the actual time elapsed (deltaTime), multiplied by the Dexterity and Reload-specific speed bonuses. The reloadTime is subsequently checked against the intended reload duration for the weapon (there's a bit of wiggle there, related to the animation process).
So yes, reloading definitely scales with Dexterity as well.