In addition, the C-130 AMP meets U.S. Special Forces requirements
That's not quite true based on my knowledge of what it would & would not do. Additionally, if what I heard from a Flight-Test Engineer is accurate, AFSOC pulled out of AMP & issued a stop-work order about two months ago. They're not happy with Boeing.
In the off chance the MoD were to contract Boeing, I'd give you this bit of advice - be sure & have a very thorough contract written. Boeing are infamous for meeting the letter of the contract & not the intent of the customer.
I have no knowledge of their "patch" or "upgrade" to CWB that would preclude having to pull it out & replace it, so can't speak to that.
As for how many hours a CWB is good for? That's a sticky subject - the answer is 30,000-45,000, but it's not that simple. USAF uses something called "equivalent baseline hours" to gauge REAL flying. So when the Air Engineers complete the post-flight engineering paperwork, there is a lot of maths to do. A baseline hour is based on straight & level unaccelerated flight at some mid-weight (135K in old money). If you do anything else, you're adding "unforseen" fatigue and the hours get muliplied by a variable determined by weight & flight regime. Heavyweight (or worse, overweight) operations whilst low-flying carry the largest penalty. So frames with 7-9K hours on them are rated at 25-28K hours due to usage - and they've got the engineering data to back this up, coupled with USAF inspections which confirm this.
At 30K EBH, there are restrictions placed on the frame (at least in the USAF). These restrictions can be removed based on a very robust & active inspection regime which costs GEs many man hours. At 40 or 45K EBH (I forget which), they are grounded & no inspections can fix it. New CWB is required.
AFSOC is feeling this more because our planes are heavier to begin with - Zero Fuel Weight ranges between 95K-115K depending on model...
The high ops tempo just makes all this happen that much quicker.