ORM has inconsistencies in evaluating LockMode::NONE throughout the classes. Using LockMode::NONE is different from using no LockMode at all because on platforms that use table lock hints, there exists an explicit hint for not locking tables at all for a specific query.
ORM's method signatures use a default value of LockMode::NONE where applicable which causes the platforms to append a "NOLOCK" table hint to the query instead of not appending any table lock hint at all.
This is a problem because a "NOLOCK" table hint changes the transaction isolation level to READ_UNCOMMITTED whereas in SQL Server for example the default transaction isolation level is READ_COMMITTED.
ORM should use "null" or "false" as default value for lock modes so that by default no table lock hint is appended to the query and the user explicitly has to specify LockMode::NONE if he desires it.
This only affects SQL Server in ORM < 2.5 and will also affect SQL Anywhere in ORM >= 2.5.