I had difficulty shifting the Quest on hot days here in Massachusetts. My hand would slip on the Gripshiift that came with the bike. I found however that Shimano thumbshifters could always be confidently shifted with sweaty hands. In addition, by going friction old school I could leave behind the fuzziness of trying to index shift a derailleur ten cable feet away. Thumbshifters are too large a diameter for standard road bar interior dimension, so I had to drill out the t-bar on the Quest to fit.
And I found for the front, since the components are standard, any triple shifter can work as long as adjusted well. Again I would choose friction operation. A granny gear may require an extra long cage.
Oh, and I found the chain wrap takeup mechanism to be inadequate for the job. I replaced it with a long aluminum lever with an idler pulley on it that takes up chain slack by lifting the return side chain actuated by a bungee cord and adjusted by a plastic cord lock. Oh, wait a minute, that's for Alleweder. The Quest actually tensions the chain just fine.
The one thing I have not figured out is how to elevate the bike and operate the drive mechanism for adjustment in the shop. Tying a stick to a pedal and letting it out a foot hole works, but is not satisfactory.