It needs to be remembered that (with the exception of 141113), the Class 141s were not upgraded from Leyland TL11 engines and SCG gearboxes to the Cummins L10 and Voith powertrain, which vastly improved reliability on the later classes of Pacers. In view of the fact that original setup could not be made to work reliably in the UK, it is hardly surprising that they wouldn't work either in a hot Middle Eastern country!
A number of years ago, preserved 141113, was loaned to the Weardale railway to cover for their failed (and now scrapped) 141103. I believe that it worked for 52 consecutive days with just routine maintenance.
Other European countries had railbuses and the Germans loved their 'Uerdingen Railbus'.
https://en.wikipedia.org/wiki/Uerdingen_railbus .
At least the later classes of Pacers were built to the full rail width of approx 2.83 metres and have wide gangways. A lot of newer rolling stock doesn't; the 185s and 350s are a prime example and it is very difficult to get down the gangway with a large shopping bag or two. I have also noticed that these units (despite having bogies) seem almost as lively as Pacers when going over points.
Another plus point that Pacers have is that they have a smaller gap between the platform and train. It would be very difficult for a passenger to fall between the train and platform boarding one. I have seen this happen twice with 150s over the years. Although the Pacers have two steps, the first is lower down than the only step on a 150 or 156.