Thanks for the reply! I use direct connect method extensively in my Py playthrough. The biggest issue seems to be that TSM doesn't balance multiple direct connect stations. If the production is less than consumption, one of the request station always get all the supply.
I also noticed the normal lamp-requester will show the time waited, and it follows a first in first out order. Such mechanism is missing for direct connect requesters. It would be nice to make the direct connect request work better. Each component in my current playthrough requires 6-7 ingredient, and being able to set it using direct connect is much simpler than setting up 6-7 lamps and decision-combinators.