If you're talking about Vgs on the wing, chances are they won't be doing much to help climb performance.
I can think of three functions for VGs, two of which are vaguely related, and one might help climb performance.
1. Shock stabilisation. A row of VGs in front of an aileron, say, or just as a row on the wing upper surface, may act to 'hold' a shock location, preventing it from wandering fore and aft, which might cause handling issues. Most versions of the BAe Hawk have one or two VG rows on the upper surface of the outboard wing for reasons such as these.
2. Stall characteristics. By acting as you described - mixing the laminar and turbulent BLs, so re-energising the BL and delaying separation, better stall characteristics and a lower stall speed may be obtained. While this may imporve some aspects of performance, it probably won't affect climb performance (which is usually optimal at much higher speeds, hence the use of 'overspeed' takeoff procedures)
3. Control of separation drag. Vgs on a 'boat-tailing' fuselage may act to re-energise the fuselage BL and delay separation until nearer the aft end. Since base drag is almost always worse than profile drag, this will usually improve fuselage drag overall, and THAT may slightly improve climb (though it's more noticeable at cruise, I wager, and may actually be there for handling not performance issues, dependent on the type)
Of course, any purist aerodynamicist will turn his or her nose up at the idea of fitting VGs; much as pilots regard the spoiler lever with some disdain, add-on fixes are in some ways an admission that we didn't get things right the first time....