I've run the numbers. **Statistically (excluding criticals) they are exactly the same.**

Here's a quick sample. Let's say you are rolling two dice.

With focus, the chance they are both hits is **6/8 * 6/8 = 36/64** (that's an easy calculation - 4 sides are hits and 2 sides are focus - so 6 sides are good results)

Now, with target lock

First, the chance they are both hits to start = **4/8 * 4/8 = 16/64 = 1/4**

But, what if the first roll doesn't hit. There are two options,

The first roll is all misses, then the reroll is all hits = 4/8 * 4/8 (misses) * 4/8 * 4/8 = **1/16**

But, if the first roll is one hit and one miss, or one miss and one hit, then 4/8 (hit) * 4/8 (miss) * 4/8 (reroll hits) **1/8 x 2 = 1/4 **

Thus the total for** target lock is 1/4 + 1/16 + 1/4 = 4/16 + 1/16 + 4/16 = 9/16 = 36/64**

Exactly the same. Here are ALL the stats….

Hard to follow, I know. But it works. No matter how many dice you roll. And I calculated all the options. Listed here

http://boardgamegeek.com/thread/856660/all-the-stats-expected-damage

Enjoy