So, I read this thread and went to purchase all of the items only to find that the Flowcooler pumps are sold out. But, I figured that's actually not a bad thing. I would rather try one mod at a time to see the true effect of each.
I went ahead and bought the fan clutch and fan listed above. I trimmed the blades and installed the fan. My Disco already runs fairly cool, but I live in the desert of AZ, so I'll take any drop in temp I can get. I never let it rise above 212 (kill the A/C, put it in neutral and rev to 1,500 rpm, etc).
My results of just adding the fan and clutch (on top of already having a newish radiator and an inline stat mod), I'm seeing a few (maybe 3 or 4) degrees lower temps driving around. The biggest thing I noticed is that I can idle for several minutes without the temp climbing really fast. It still climbs but I was able to idle in my driveway for 15 minutes with the A/C on in 108 degree weather and I only saw 204.8. That's unheard of. Normally it would climb to 208 - 210 and I'd have a panic attack and rev the engine a bit to bring it down.
The other thing I notice is the temps don't fluctuate as much. It's more steady.
Some rough numbers:
108 degrees ambient, 160 degree IAT
City driving 50ish MPH with stop lights:
Before: 197 - 204 After: 194 - 201
Long idle during the day
Before: 201 - 210 After 199 - 204.8 (touched 206 for a second and back to 204.8)
I haven't hit the freeway yet, but I'd guess it won't make much difference there.
I call this a success. It's not huge difference, but every little bit counts. Once the Flowcooler pump is back in stock, I'll add that and see what it's impact is.