I"ve read several comments that the magnified area of the dial is a big hit with us older bifocaled crowd. I finally was forced to get them in August. I really struggle to read the small red print on the body of the 15TDCL and the UTM scales on the 8099's UTM card.

The 15TDCL would work just fine one-handed but on mine the dial isn't nearly as smooth-turning as the 8099, so it is kind of hard to rotate one-handed with a thumb. It can be done though. There is no way I can flip the 15TDCL open one-handed without using toes too. The 8099 can be flipped open one-handed, but it is awkward.

I'll assume you have a newer verson of the 8099 - with the green forward bearing numbers on the outside of the dial. Consider yourself lucky. For some reason I only use the old one thinking that I'm saving the new one for my son or something. The reality is that having the green numbers on the inside of the dial does make them hard to read.

In the older one they also had the black backbearing numbers backward under the philosophy that you'd use them when using the compass & mirror backwards - what they call "reverse mirror sighting" (kind of like the old press cameras where you look down on the mirror) - when backwards the black numbers would be the facing up - it kind of made sense. I think the reality is that users didn't use the compass that way and more often used the black numbers as back bearings while holding the compass at eye-level. So now the newer version has both green & black numbers facing the same way.

I should start using the new one and let my son (with better eyesight) use the older one.

I finally got around to doing more repeated measures (in the house - its been raining all day today) and I continue to get +/- 1 degree (a 2 degree range) for both the 8099 and the 15TDCL, but do find boxing the 15DTCL needle harder. Hmmm, I just realized that the problem might be related to the colors involved. On my 15DTCL both the north end of the needle and the north end of the box are red and I find it hard to see the red line of the box next to the red part of the needle. The south ends use a white needle and a black box so that is easier to see.

Ken