The answer is NO, you do not lose your Reaping Mauler class features, and YES, you do lose the benefits of Clever Wrestling. The confusion seems to stem from the Complete Warrior's text describing Prestige Class requirements, something no other book (including the DMG and thus the SRD) details.
Meeting Class Requirements: It's possible for a character to take levels in a prestige class and later be in a position where the character no longer qualifies to be a member of the class. An alignment change, levels lost because of character death, or the less of a magic item that granted an important ability are examples of events that make a character ineligible for advance farther in a prestige class.
If a character no longer meets the requirements for a prestige class, he or she loses the benefit of any class features or other special abilities granted by the class
The first line I highlighted seems to mirror and build upon what the DMG and SRD say:
...characters must meet Requirements before they can take their first level of a prestige class. The rules for level advancement apply to this system, meaning the first step of advancement is always choosing a class. If a character does not meet the Requirements for a prestige class before that first step, that character cannot take the first level of that prestige class.
So it suggests that a character needs to keep meeting the requirements of the class in order to continue advancing along it.
The second line I highlighted, the "he or she loses the benefit of any class features or other special abilities granted by the class" bit, seems to exist only in the Complete Warrior (it's not even in the Complete Divine, where things like alignment qualifications might be more relevant). I think the rule makes sense, but has been stretched to create these dilemmas because it's not particularly specific.
Here's what the PHB/SRD has to say about feat prerequsites:
Some feats have prerequisites. Your character must have the indicated ability score, class feature, feat, skill, base attack bonus, or other quality designated in order to select or use that feat. A character can gain a feat at the same level at which he or she gains the prerequisite.
A character can’t use a feat if he or she has lost a prerequisite.
"Can't use" I think is the keystone to this argument, because you don't lose the feat. You still have the feat, which means you still qualify for the prestige class.
By the same token, a rogue or ranger who puts on half plate doesn't immediately lose access to every ability he's picked up from a prestige class with evasion as a requirement.
