As Damian says, now is a good time to get an ADC if you don’t already have one. About the price of a good eyepiece and a sound investment especially if you want to image or view Mars and Saturn from the UK in the next few years.
Es Reid and I did a study of the levels of astigmatism generated by ADCs in use and we found that for a given scope the degree of astigmatism generated by a correctly adjusted ADC is primarily related to the altitude of the object. You can read more about this study at; http://www.skyinspector.co.uk/adcs-part2
I also have a more general page on ADCs those those interested in learning more about these useful devices at; http://www.skyinspector.co.uk/atm-dispersion-corrector–adc