It helps to know that Part M is not really new, it's a modified version of the present French system which works well. Part M brings in new opportunities for SOME UK owners to get involved with maintenance and save money. However if you simply fly your aeroplane and never open the cowlings, & pass it to the engineers for all servicing; then it's going to cost more.
But for those pilots with an engineering background who enjoy getting their hands dirty, part M gives you the chance to look after some (not all) certified EASA type aircraft in much the same way as LAA members do for their permit types.
However the aircraft has to be a simple single engine non-commercial type below 2730 kgs, it has to have a type specific maintenance programme, (generally only available to French & German aircraft), and you need to be working in the "Uncontrolled environment". Your ARC will need to be renewed every year, but this can be done by ANY part G & I company in ANY EU member state. (Choose the state with the lowest regulatory costs)
Much of your time will be spent on keeping documentation updated, it is not for nothing that EASA considered it advisable to create a separate part G organisation to manage the paperwork. Indeed if your aircraft is not a very simple type, don't even think of going the uncontrolled route, it's not worth the hassle. But for some aircraft it is possible for a competant owner to carry out 50 hour and Annual checks using the detailed instructions (what to do and when to do it) in the type specific maintenance programme. Always keeping an eye on the pilot/owner task list in Appendix VIII Like I said, it's not for everyone, and you still have to get a LAE to sign up the ADs, and deal with items of servicing beyond your level of competance. Above all don't just sit back and moan about part M, it gives possibilities for perfectly legal creative interpretation of the regulations.