Im usually riding on Zwift with my retro 2x6 speed steel bike.
recently I used my 2x11 ultegra road bike, whilst I replace the bb on the above bike)
Yes you have more intermediate gears ( overall range can be changed using the misnamed “trainer difficulty”)
but honestly it didn’t make much difference. perhaps more gear changing and less cadence changing but hardly noticeable.
( other than I kept reaching for the down tube shifters ! 
I recently upgraded the groupset on the bike I ride indoors from 10-speed 105 to 11-speed Ultegra. I had gotten my several years and miles out of the original components and it was just time. There’s nothing wrong with the frame so the cost (approx 600 USD plus my time & patience) was cheaper than picking out and getting fitted for a new bike.
Was it worth it to me? Definitely but I never expected it to upgrade my performance on Zwift. Right now I’m still working to get back in shape after an injury and still using the same power meter, so power is power. But the shifting experience is definitely smoother. It’s up TO YOU when all is said and done.
Thank you folks for the advise. I think I have enough input to justify sticking with whatever I have now