I have a similar experience, but from Nighthawk. Their factory gun came with 2 mags, but they sent a coupon offer for ( 6 ) more mags for $99. These were top quality mags, endorsed by the manufacturer, and I jumped all over it. I never looked back.
If your factory gun shoots well with the factory mags, and you are buying the same quality mags, I would get as many as you could afford and keep them around.
Half the mags I bought got tried out once at the range for multiple runs, then were put back in the bags and stored in the safe for use later on.
Just my thoughts on this, but if the OEM is offering to sell them to you, they are probably pretty certain they will work well with the product they sold you.