Out of curiosity, I checked a selection of off-peak trips before and after the change from bus to train, from Barrie Terminal to Union:
Weekday midday NB:
June 2017:
Departs Union 9:10, 10:10, 11:10 etc
75 minutes to East Gwillimbury
5 minutes transfer
65 minutes to Barrie Bus Terminal
Total: 145 minutes
January 2018:
Departs Union 9:40, 10:40 11:40 etc
49 minutes to Aurora
8 minutes transfer
90 minutes to Barrie Bus Terminal
Total: 147 minutes
Travel time change: +2 minutes
Weekday midday SB:
June 2017:
Departs Barrie Bus Terminal at 9:45, 10:45, 11:45 etc
65 minutes to East Gwillimbury
5 minutes transfer
75 minutes to Union
Total: 145 minutes
January 2018:
Departs Barrie Bus Terminal at 9:51, 10:51, 11:51 etc
95 minutes to Aurora
15 minutes transfer
52 minutes to Union
Total: 162 minutes
Travel time change: +17 minutes
So between Barrie and Toronto, the northbound trip is the same speed as before, though with the train being probably more reliable than the bus, trips might actually be faster in practice. The big change is the southbound trip which is considerably slower, and almost all of the added time is due to an increased transfer time. That time needed to be increased because while the connecting bus at East Gwillimbury used to hold for the southbound arrival from Barrie, the train does not. Holding the train for a late bus is not an option because the train needs to arrive at the siding at the right time to meet the northbound train.
But anyone travelling between Barrie and downtown Toronto in a hurry should probably just take the intercity services operated by Greyhound and Ontario Northland which do the same trip in 90 minutes. The real change is for people in Newmarket who used to have a direct bus to downtown in 63 minutes from Newmarket Terminal, and now have an indirect trip which takes 83 minutes.
I think GO has the right idea with their 3 connecting buses:
69 to Newmarket Terminal
68 to Barrie Terminal via Newmarket GO
69A to Wellington/404 Park & Ride
But more could be done to improve access to the train from the north.
Route 69A Aurora - Aurora P&R
It's interesting that GO created this route, shuttling between the GO station and the Wellington/404 Park & Ride lot. This service could allow that lot to act as an overflow lot for Aurora station, except that the bus only runs outside of peak periods. So anyone who might travel during the peak period in either direction of their trip wouldn't be able to use it.
I think the route could be expanded to all day (including peak periods), and extended north to Sutton, replacing YRT's route 50 (Newmarket Terminal - Sutton via Davis Drive). It would serve Newmarket's Davis/404 bus terminal, which would connect it to the Viva Yellow BRT line, and DRT route 960 from Uxbridge.
Route 68 Aurora - Barrie; Route 69 Newmarket Terminal - Aurora
Currently Route 68 provides local service for its entire length, which makes it painfully slow. It takes 90 minutes just to get from Allandale to Aurora, whereas off-peak trains take 95 minutes to do the entire route from Allandale to Union! The portion between Barrie and Bradford provides essential local service to that area which is otherwise unserved, but the portion between Bradford and Aurora should operate express, with YRT covering the local service.
Currently Route 68 gets off of Highway 11 to drive through the centre of Holland Landing. Meanwhile YRT's route 52 runs roughly every hour from Holland Landing to Newmarket Bus Terminal.
By combining YRT's route 52 (Holland Landing - Newmarket Terminal) with GO's route 69 (Newmarket Terminal - Aurora GO), Holland Landing would then have direct access to the GO train via Newmarket Terminal, allowing GO's route 68 to blast non-stop down Highway 11 from East Gwillimbury station to Bradford station.
View attachment 131349
While the connecting buses themselves will not be as fast as a direct train or a direct bus, the fact that there are 3 north-south routes through Newmarket would means that this is somewhat offset by better coverage. In other words, although the bus takes longer, it takes you less time to get to the bus.