I am also interested to hear opinions. Pg 93 of the 2005 Elise manual states “If severe damage is caused to a composite panel where the underlying structure is broken, repairs may take the form of panel replacement, or of panel repair using techniques where new composite material is integrated with the old to result in undiminished panel strength.” In my reading of the page, they are clearly referring to body parts including the clams.
It is also somewhat amusing that they describe the benefits of the clam design as: “to allow simple and economic accident repair.”
This "advice" has been floating around for years. As far as I know the reason for it is more Lotus CYA than anything else. The elise clams are injection molded fiberglass which is a somewhat unique technique for producing the part.
If you find someone with good expertise in fiberglass, they should be able to perform a proper repair that doesn't result in bubbling or cracking down the line. I think that the small nature of lotus dealer network, and the inability for them to guarantee fiberglass work, leads to some of the advice you hear about replacing the part rather than repairing it.
The rub is that OEM clams can feature long waiting times and will also have to be "worked" to fit onto any car. You're definitely not saving any money or structural integrity with a clam replacement. You are incurring larger expense and time to getting your car back on the road in order to avoid the risk of poor quality repair work.
Based on what AndrewIndy posted, it appears Lotus condones clam repair.
In my case, I have some accident damage to my front clam. To convince my insurance company to pay thousands more dollars to buy a new clam, rather than repair the old one, I would need some written documentation from Lotus saying calm repair is not recommended.
Otherwise, it looks I will be repairing the old clam.