I computed my general kitchen lighting needs based on the following
total_sq_footage * lumens_per_sq_ft / output_per_recessed_can

lumens_per_sq_ft in my case was 35
output_per_recessed_can was 600 ( deliberately derated output of a LR6). The output was diffuse and unlike a standard recessed can light.

In your situation. a naked 60 watt incandescent bulb outputs ~ 800 lumens.
Assuming that the fixtures are surface mounted with some shading which reduces the output per bulb to ~ 700

Total light output from the existing would be 6 * 700 = 4200 lumens.

GU10 reflector lights will have very directional and focussed light output which may not be suitable for lighting the entire kitchen.

In addition, if you live in a jurisdiction which mandates energy efficiency laws (e.g. - title 24), halogen lights cannot be used as the primary light source.

Title 24 mandates that 50% of the wattage used for lighting be devoted to energy efficient light sources (i.e. - fluorescent or LED).