Re: Equivalent of Vic Firth Steve Gadd sticks
The Steve Gadd signature is L = 15 3/4" Dia = .550" with a barrel tip. (hickory)
Fitting these criteria best at Vic Firth are those 2 models:
HD4 L = 15 7/8" Dia = .530" with a barrel tip. (hickory)
SD4 Combo L = 15 7/8" Dia = .545" with a barrel tip. (maple)
You can also browse other brands, most manufacturer give a length, diameter, type of tip and wood species info for their models, select and try those with a similar tip, size and weight.
You could probably try and compare them against a SG stick in a shop once you've done the homework of selecting a few contenders.
Keep On Drumming