Pretty much all electronics these days use a "chopper" power supply, meaning the 230v mains is rectified to 380 VDC, or 120v to 170v, filtered and chopped at high frequency (using squarewave PWM) so as to use very small transformers to arrive at the low voltage DC required.
Therefore it matters not the shape, or frequency even DC of the input mains waveform, and even the voltage over very loose limits. Many modern devices are designed for the global market to happily accept an input AC voltage between 80 to 260 volts with no changes needed, or even DC for that matter.
CFL bulbs will run on AC or DC too and are voltage tolerant. Many mains LED bulbs require AC, as the cheapies use a capacitance dropper. DC wont harm these, they just wont work. Running CFLs on DC reduces radio interferrence dramatically and can increase brightness on some..
Induction motors will run warmer on square waves, as will anything using the old fashioned mains transformer. The inductance of the windings heat as they attempt to convert the square wave to a sine. Any inductance will oppose a voltage change.
My electronics workshop runs completely from a 600 watt sinewave inverter as does most of my test gear, signal generators, oscilloscopes and spectrum analysers use linear power supplies, inbuilt switched mode choppers are just too noisy for this sensitive precision equipment. My lighting is DC 200v
My 6kva generator unit is 240 volt AVR'd, the cheaper brushless types have voltage surge issues ,when a large load is suddenly disconnected, the output voltage will spike badly because of the slow time constant of the phasing capacitor.... thats the round white thing that fails regularly in these designs.
The only effect mains frequency will have, is on the speed of induction motors, and any clock that uses mains frequency as a clock timing signal, ie, very few appliances these days.
Things like vacuum cleaners, electric angle grinders etc using brushed "universal" motors will be voltage and frequency tolerant, and will run the same even on DC.. ie, a frequency of zero.
Washing machines, refrigerator compressors using induction motors just want AC, 45 to 65 Hz you wont notice much difference.
Most modern caddy inverter type MIG/MMA/TIG welders will also run on AC/DC as they too directly rectify the mains, and care not as regards mains frequency. Running stuff on DC if you can makes sense, as the appliance is more efficient as there are no power factor issues , but care is needed, DC will quickly fry an induction motor if accidentally connected.
Oddly, and contrary to accepted opinion, modern electronic devices , because of the cheap chopper type shitty power supplies they have built in, are now more tolerant of shitty mains power than ever, as they have very good post filtering and extra MOV/VDR protection in place to mitigate the shitty power supply they use. If in doubt, hold an AM radio near a SMPS power supply brick and listen to the harmonics.
Anything thats a pure resistance, ie water and space heating, cooking elements etc are also voltage and frequency tolerant, and give identical performance on DC.... there are no power factor issues even when used on AC.
So, spending great effort to govern an engine to give exactly 50/60 Hz is really a waste of time and money.
Worrying too much about absolute voltages is also not necessary, just avoid fast voltage spikes and changes.
The problem witth aluminium windings remains.
Cheap welding equipment also use aluminium wire, and over many years of repairing this stuff for a living, have found soaking the coils/windings/transformers in old fashioned boiled linseed oil, or any vege oil for that matter will prevent the corrosion that eventually causes shorted turns as the metal swells and ruptures the insulation. This will also work on armatures and stators. It takes just one shorted turn to destroy the equipment. The oil will seep into the windings, stay semi flexible with movement and cover the wire with an air/moisture barrier
Alumimium is a relatively poor electrical conductor and will heat more in use, this causes relative expansive movement between windings and will stress fixed insulation over time.
The Chinese have also invented a way to copper plate aluminium, so a simple visual check may reveal nothing unusual. This deception is even worse, as electrolytic corrosion takes place at a rapid rate.... dissimilar metals.
The old and tested way to judge quality in a generator is LOTS of copper and LOTS and LOTS of iron... ie, choose the heaviest one. Go for larger diameters rather than longer length. Large diameters also indicate more poles, and lower rotation speeds.
Waveform discontinuities/distortion are mostly caused by core saturation, older generators had tertiary windings to advance/retard the magnetic flux under different loading but were expensive needing extra poles on the rotor, thats why they were much larger, and exaggerated by requiring a seperate exciter.... A good modern AVR will usually sort these out, oddly more usual at light loading.
These are just my observations over time.
