Good that you are upgrading those Sora's. They are just not fast enough! The 105 are excellent entry level shifters from Shimano and you will like them. I rode on them for 2 years and just upgraded them with Dura Ace while the 105's replaced the Sora's on my wife's trek 1000.
A quick remark regarding your ride thru TFN, I have been on the forum for a year now and I have always followed your rides and reports. The way you rode TFN was just amazing and I have never seen anybody improve so much in a small time frame! Your hard work and determination paid off and congratulations!!
Please don't save humanity. The planet will thank you.
Dogma 65.1, Dogma 60.1, Storck Absolutist, Colnago K Zero TT, Ridley X Fire (disc), Pinarello Paris, Ferrari Colnago Ltd Edition, Bianchi Volpe .... etc etc