I can offer some comments on the Silvia, since I have one.
Can you leave it on 24/7 without damage - yes. Mine is on 12-15 hours a day 7 days a week (Ive had it about 5 years), and Ive been told theres no harm in it being always on.
Can it do 4 coffees at a time - yes.
Fast heat-up - well I prefer to let it half an hour to warm up in the mornings, but theres no question you can physically make the first coffee within 5 minutes of turning it on.
Maintenance - the water tank needs to be manually checked and refilled once a day. With a lot of use that might be twice a day.
The Silvia is solid & reliable, and easy to use.
Hopefully someone can compare it to the Lelit?
Depending on what city youre in, maybe you could try another visit to a shop after you get some advice here - the more you know, the easier it gets to walk into a shop and see if they can help. Before you buy, you want demonstrations, plus a chance to make coffee yourself on each machine.
Some of the people on this forum sell the Silvia and the Lelit, and they come well recommended.