I'm running Claris 3 x 8 on my 1993 Bridgestone XO-2. The stuff works very well and it has taken a beating. Plus it shifts well over a non-shimano triple; no complaints here.

I'm not sure which version of Claris and 105 you've tried but both of mine are 3 years old and the 105 is clearly much better then Claris in shifting crispness, precision, smoothness, and stopping...but stopping is probably an issue with the Claris pads. My wife has the 3x8 while my 105 is 2x10, but the rear shifting on the 105 is superior as is the front shifting but that could be due to hers having the triple system but I think even if it was a double it wouldn't shift quite as well. I keep my bikes clean so I can't report on the dirty cable and housing thing, but after 3 seasons neither are experiencing any odd sensitivity issues. Even my original cables and chains on both bikes, with my 105 having over 8,000 miles on it are all still in great shape.

Don't know what that is, but the Sora I saw in person at the bike shop the last couple of years didn't have the thumb shifters.

[MENTION=205284]rekmeyata[/MENTION] You can see the cable release thumb buttons hanging down like beagle ears in this photo of the 3400 shifters, below and behind the cable output. (photo from Chain Reaction). These don't have the release lever behind the brake lever like the 3500. What you see as a button on the 3500 shifter, is actually the output for the shifter cable, which on the 3500 also has a barrel adjuster, making it look big. The new Sora R3000 has aero shifter cables and nothing hanging off.

105 5703, 3x10.

Claris was 2x8, not sure of the model number.

105 shifting was quicker, but 2x8 was more precise, especially when cables/housing gets a bit older.

My conclusion was it was down to cable pull and cog spacing. Since the 105 RD was top class.

I see that now, I thought the protrusion was a lever from the angle I saw it. thanks for bringing that to light..

Not sure why the perceived difference is that we both experienced, but from my experience the 105 is definitely better all the way around. There is one thing I need to mentioned that I failed to do so. I test rode bikes with all 105, based on those test rides it was better than Claris, my bike however has Ultegra rear derailleur not the 105, everything else is 105 except the cables which are DA9000 cables, that system setup is a day and night difference against Claris.

I had bikes set up:
SP41 housing and cables (Shimano)

One had 105 RD, the other had Sora RD.

Strava says I'm just shy of 6200 miles on my 3x8 commuter, the Claris has been nothing but solid and dependable the whole time.

[MENTION=203765]Axiom[/MENTION] if you do change out, I'd be happy to take those 600 shifters off your hands if you don't want them.

I have Claris 2400 on my gravel bike. Its 2016 Specialized Diverge. The only thing I'm not a fan of are the cables sticking out of it. I have over 1000 miles on this groupset and never had any problems with it so far. It shifts pretty smooth. It is 2x8, so gear jumps are larger, but you get used to it once you build up your legs. I am planning on possibly upgrading, but I'm not in a hurry yet. I don't compete or race, so there is no need.