A 52 chainring is 4% higher than a 50. That's about a half shift. (Each shift depends on the two tooth counts of the rear cog, ranging from around 5% up to 12+%)
Below: Charts of mph ranges for each shift at typical flat road cadences. I extended the cadence to 99 so that all the charts would extend to 40 mph, it otherwise scales the charts smaller.
Your 34/50 and 11-28:
A 36/52 and 11-28:
Each gear combination is shifted to a slightly faster speed, about 1/3 to 1/2 of a shift. Around 1 mph at 20 mph in the big ring.
It's a fairly subtle change.
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Sram's 11-28 has different gearing than Shimano's 11-28.
Compare this chart to the top 50/34 chart. The Sram gearing has closer shifts above 20 mph, wider gaps in the 15-20 mph range. A lot of riders like having a 16 cog. It's a better choice for "A group" or racing riders.
34/50 and 11-28 Sram:
