Is HiLo more efficient than autoincrement bigint? (and another questions)

Question

I have some questions about HiLo.

1. I have seen in examples that if I use HiLo, in the database it is created sequence files to asign the ID. I am wondering what happen if one client use for example HiLo but another client doesn't use it. Is it compatible or I could have problems?

2. About performance, to get the Hi value, I guess it is needed a roundtrip to the database to get the range. So wouldn't it be better to avoid this and let the database assign the ID as autoincrement?

3. About concurrency, and perhaps it is related with performance. When a Hi value is assigned to a client, i guess the range is block for the rest clients, so wouldn't it make the performance would be worse? And what happen if a client doesn't commit the add?

4. If I use DDD, how the root entity is responsible of the consistent of the data, so don't need the IDs really, just the references of the objects, is it useful to use HiLo?

Thanks.