Peter, if you search back postings you will find probably hundreds of contributions on this topic.
From personal experience a mover is very much worth having, particularly if you have difficult parking access at home, go onto European sites much or are not as young as you used to be - or any of the above. They are also quite good for avoiding "domestics"
Again personally I have and would recommend Powrtouch but you will read others who swear by Riech / Truma or others. Look at the warranties as well as the base purchase price. Fitting yourself is not too difficult if you are reasonably DIY handy - this way you know how the job has been done and where everything is, and save yourself