Against churchill, yes.
Against IS-2 or KV-1/2, no.
Same with brummbar vs ostwind vs single squads and blobs.
In 5 duels with IS2 vs double stugs or panther:
Stugs win 4 out of 5 fights
Panther wins 1 out of 5 fights
In a series of 5 duels with 2 stugs vs kv-1 and panther vs kv-1
Stugs win all 5 fights, KV-1 manages to kill 2 stugs in different duels
Panther wins only 4 fights
In a trial of 2 brumbar vs 5 guards squads, and 3 ostwinds vs 5 guards squads
7 guards models remain from fighting 2 brumbars
6 guards models remain from fighting 3 ostwinds
In short t3 is the most cost effective vehicle tier for OST. It is at a minimum equal which means teching to t4 is a waste of resources and time.