Having worked in the business for a while, and also bought a property, I would say just tread carefully. Some of them sound great, some sound terrible. As I understand it, they often consist of several junior staff working under one trained solicitor who signs off the work. In practice this can cause the issues outlined above with documents being asked for twice or not asked for at all etc.
Then again, I’ve heard of purchases almost derailed by local solicitors not keeping up to speed either.
I would not have thought than an online solicitor would be any faster or slower by default. The people I bought from had an online conveyancer, and they held the process up.
The solicitor I had for my purchase was a local guy in town and an absolute Rottweiler; exactly the sort of person you’d want to have representing you when dealing with your home and life savings.
So I have no strong feelings either way, but that’s who I put my trust and money in. There’s good options and bad options on both sides, but do be be picky, and don’t be pushed by estate agents/other salespeople.