As Squawk implies, some form of automated tracking for airline ops is a no-brainer in the 21st century and there are a number of solutions which would work well enough given the modest data transfer rates involved. For private operations, my own preference is for an on-demand system, simply because I'm old-fashioned enough to think my private flight details should not be routinely available to all and sundry, mandatory IFR ADSB upgrades notwithstanding.
I also believe that some of the criticism of fixed ELTs is misplaced. Having looked a a few GA installations prior to upgrading to a modest 406 MHz ELT system, I noted that some failed elementary radio engineering common sense criteria: simple things like lengths of antenna cable and position of strain loops. I'd also comment that the construction quality of some of the TSO'd ELTs and the readily available EPIRBs I've examined would make me very wary of entering into any religious argument about which is the superior solution. I was quite happy to spend a few hundred dollars on the aircraft ELT and to buy an additional EPIRB for general recreational use, including longer trips in the aircraft. Even then I don't fool myself that there's a 100% probabilty of successful transmission on the basis of either g-switch or human activation.