Unless you test each piece of equipment there is really no reliabkle way to know. I used to specify dul frequency 50/60 hz equipment but after a couple of years we learned the hard way equipment often failed prematurely on 50Hz. Things that definitely do not like 50HZ in the dual frequency catagory are induction motors ferro resonant power supplies or chargers, /tv VCR and microwaves.
Almost any transformer based device will be optimized for one or the other frequencies and does not like the alternative. I have learned that 50Hz equipment seems to live longer on 60Hz than 60 hz running on 50Hz.
In terms of power fronm the generator you are going to lose 20%. If you based your load calculations on having 7kW this could hurt. Running at the lower speed you will find the inductive loads will pull more current and run hot. This also tends to skew your power budget.
I once modified a 9 KW 60 hz genset to run at 50hz but we kept blowing the start caps on a pump motor supposedly rated 50/60 hz. Finally after a year all the motor appliances had to be changed out. Quite an expense.
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