Do you want to save for an early gem when playing against techies? Constantly buying sentries seems like a hug drain on the supports.
I played as CM up against Techies and eventually decided to get a gem. It was working okay until I died, and then our PL decided to walk past it twice with 2 slots open.
I think Techies are annoying and not fun to play against right now, but once people learn to play against them it'll be fine.