Disagree. I use the sleeper to Glasgow and occasionally others several times a year for business travel. Leave home about 10pm and arrive in Glasgow with time for a shower and breakfast, and often a local train out of the city, before meetings at 9am. Either catch a day train back in the afternoon or the sleeper home. Alternative of air would mean leaving home at 4am, driving to airport, hiring car at Glasgow, with all the hassle that entails. No comparison, sleeper wins for me every time.
The inability to hire cars at main railways stations especially out of business hours is one of the main drawbacks for me.
If you are doing more than one meeting in Scotland its pretty much impossible to do that by public transport and you have security issues when you have a lot of papers etc with you.
I typically leave home at 5.30 having checked in on line and get a flight leaving at around 7.30
to either Glasgow or Edinburgh. Hire a car with AVIIS or Hertz if you are a regular user that takes no more than 10 mins.
First meeting at 10.30 giving time for breakfast enroute. Usually manage 3 to 4 jobs in the central belt before getting a flight home from the nearest airport at 7 to 9 ish. Generally takes about 1 hr 25 mins from touchdown to front door.
I like the fact that you are somehow still using the sleeper in this day and age but it can hardly be cost effective for your business