Well, I'm sure you know, that a Matrix Purchase gets a free Steam key.
But a Steam purchase has no connection to Matrix.
The auto install is indeed nice. I occasionally use it when feeling lazy. Not all my Steam games are Matrix, so it's unavoidable, I usually have Steam installed.
Matrix really shines, in that it allies zero internet activity once purchased. So an offline computer isn't a problem. I currently have my main rig, and my mainly wargaming rig. The latter is not always online.
But, to answer your question, you can't really link a Steam purchase to here to begin with. So there's no 'practical' to begin with as well.
Wargame, 05% of the time.
Play with Barbies 05% of the time.
Play with Legos 10% of the time.
Build models 20% of the time
Shopping 60% of the time.
Exlains why I buy em more than I play em.