No matter how much people hate pacers, they will always be regarded as saviours of many branch lines at the end end of the day.
As I have said several times, i'm still not convinced for the following reasons:
1) Plenty of branchlines and basic railways have survived without Pacers which leads me to suspect that there are several other factors some of them political which would have impacted on the final decision as to whether to keep a branch line open more than the day - to - day cost of running one type of train rather than another. It also suggests that other cost savings such as de-staffing, single tracking etc would have been far more significant in saving such lines.
2) I've yet to see any concrete evidence that Pacers are significantly cheaper to run than other types of unit anyway (although I have asked whether this existed in a previous post and am still open to someone coming up with it)
3) As far as day-to-day running costs are concerned, I would have thought that staffing costs, fuel costs of running any train at all, and route maintenance costs would be far more significant than the difference in the day-to-day running costs of one unit over another - so much so as to render such a difference insignificant in any final decision whether to keep a branchline open or not.
4) Whilst the Pacers were no doubt cheaper to build than other units from the same era, If they hadn't been built I still suspect that we may just have had a slower replacement of the heritage fleet with the other types of train, such as 150's 153's etc.
5) As a previous poster has pointed out, many of the Pacers don't operate on branchlines at all, but instead work on secondary and commuter routes which would have been difficult to close from a planning or political point of view.
6) I think most services that aren't profitable are subsidised on the basis of how useful they are to the community, therefore their continued operation relies on the number of bums on seats. Since the Pacers are a cramped lower quality passenger environment than pretty much any other unit, I wonder whether they might actually put people off using the train and to an extent supress demand on these services, actually damaging the case for keeping them open in comparison to other units.