Threat Set - stats comparisions?

I am currently working on a threat set. My tanking gear so far has had a big survivability focus. Now the three obvious stats to shoot for in a threat set are:

Hit Rating
Expertise
Shield Block Value

Now, I have a hard time comparing these values to each others. Has anyone done any such testing or computing? If so a link to any resources would be great. For example how much SBV would 1 hit rating be comparable to in a TPS sense. I understand that this of course would depend on your DPS and how often you use shield slam etc. But still...

20 hit rating, 40 SBV, what would you pick?

From my own threat comparison spreadsheet.....

Relative Threat Comparisons:

Total TPS: 815.2

The following will add approx. 11 TPS with current gear setup:
1. 2% Threat enchant gloves
2. 50 SBV (raw before talented 30% bonus)
3. 200 AP
4. 44 Crit rating (2%)
5. 10 exp rating (.63%)
6. 20 hit rating (1.27%)
7. 66 agility

The following will add approx.18 TPS with current gear setup:
1. T6 4 piece bonus

The following will add approx.15 TPS with current gear setup:
1. Increasing weapon dps by 10
2. Decreasing weapon speed by 0.1