The biggest complaint about the plastic Griptilians is the sound they make when opening and closing. Needless to say, the Wilkins solves that problem.
As far as the strength and feel of the two grips goes, the origional was pretty good.
The WilkinsGrips turns it into a more solid feeling folder for sure.
It feels like the Pardue (522?) folder that BM used to make. It had solid aluminium handles and was one of the first true 'tank' knives.
The Pardue 522 is the Presidio lightweight. It has similar handle's as the Griptilan. Maybe you're thinking of the 520 Presidio which is still being made. Its got a pretty thick handle, good blade, but not the most comfortable carrying in the pocket. The discontinued Pardue that I like the most was the Pardue 720's. Its one of the most comfortable handle's made & feels great in the pocket.
I know what you mean by the Grip's cheap feeling FRN handle. I'd love to see a G10 one made by Benchmade. It should'nt have to cost $140 more. They make plenty of G10 folders that are'nt that expensive.
I don't understand the sound difference between the plastic Grip's and the G10 handle. I have both types and the sound is similar to me. I know the feel is different.
As for the original question.
I don't have an Umnumzann but I do have a Sebenza and its the standard which other folders are measured to. Also I think the resale value would be higher.The Ritter/Wilkins Grip will end up costing around $100 less than the Umnumzann. Will it be better for my needs? Or is the Umnumzaan going to be so superior that I should just forget the Grip and go for it?
If you're using this for moderate field use and kitchen work you should think about the Benchmade 710. Its a great folder and if you can do a search to look up the Joe Talmaldge (? spelling) article on how to get the max. sharpening out of the slight recurve blade. The 710 is already a classic.