TBH if an M car has got to 150k without that sort of preventative maintenance it has done well, rod bearings are a wearable item and a serviceable part.
If i still had my M car I would have the rod bearings changed at around 80-90k just for my own piece of mind and at the same time I would have the engine mounts replaced too.
It depends how the engine has been treated and although this isn't in the service scheme for the S54 from factory, it is a serviceable item as the bearing is a wearable surface, it is between the crankshaft and the rod, if these two surfaces met they would wear each other out very quickly hence the need for the bearing. The tolerances then give enough space for a thin film of oil to add as lubrication, but if the engine is hammered from cold the oil circulation will not work to its potential therefore they wear out quicker. There is also an inherent problem with the engine design too, when the piston is on its compression stroke and the mixture is ignited a tremendous pressure is imparted on the top of the piston, down the wrist pin, through the rod, and into the rod bearing. Some engines have trouble or weakness upwards of this chain but what the S54 does is squeeze out all the oil causing the bearing to wear on the top side.
So even if the engine is treated well, wear is inevitable and as these cars were performance bargains a few years ago a lot have been hammered probably more so M3s as so many more were made and how cheap they are.
What yorkie says is true oil maintenance is key frequent changes etc. What you can have done if you are worried is have an oil analysis, this will show up any tiny metal fragments which will give you an idea of the health of the bearings and you can make a decision from there. You can't really have the bearings inspected as it needs half the engine taking apart to get to them so if they are inspected you might as well swap them while your there.
But this is only half the story, if you haven't owned the car or engine from new you cannot be sure the engine has been treated well all its life, the risk obviously increases as the age and milage of the car increases and buying a high miler is a risk for this reason, but is preventative and knowledge is key and you have to be a bit of a geek with these engines if you want them to run well for the long haul.
TBH its not VERY expensive for preventative measures as your taking the engine apart you may as well have the engine mounts swapped too, depending on their age etc you might as well have them done, so the bearings, mounts and labour will cost around £1500. It is worth it imo simply because… as you know an engine swap is expensive and if your getting a new engine your looking at 10+k before labour.
As to the types of bearings, I would stay clear from a coated bearing as if this adds material to the bearing therefore reducing the bearing clearance on the crankshaft so the tolerance becomes smaller therefore the film will be thinner and even more wear will occur. Some bearings coatings are designed to allow the bearing to retain more oil but that doesn't change the fact that the coating will create a smaller tolerance so whether that is a benefit or not… I can't tell you. The other way of trying to solve the problem which is what BMW did originally when the early models were failing was increase the viscosity of the oil and increase the bearing tolerance. Other options for the more hard core track day oriented people or if you want to race the car is to increase oil pressure preventing oil starvation, a lot of S54s that race have a dry sump. Bit OTT for the road tho and the cost is anywhere from £2.5k upward.
So what I would do is have the OEM bearings replaced and you shouldn't have any more trouble for another 80-90k. But have an oil analysis done first to see if your engine is actually having trouble.
A lot of engine bearing trouble and information comes from race teams who blow engines, especially in the early days and these engines are pressed hard for most of the time they are run. Many sources say you should have the bearings replaced every 50k at that rate… but I think 80-90k on a normal car seems not too bad.
This is actually a great thread. So many people on this forum say how perfect the engine is and for a high performance engine of its type it is reliable but they do go… and like I said these items are replaceable because they wear out!!!
All high performance engines suffer this, it is enviable. From AMGs, Ms, 911s, Lambos, Ferraris etc etc all high performance small tolerance naturally aspirated engines have this issue.
i'm currently on 79,700 so waiting for the grind & bang shouldn't take long 
Liverpool
The things I talked about is zero speculation and only based on facts! I strongly advice everyone with a s54 engine to get the bearing shells replaced every 80.000 - 100.000km. I know 5x people with a s54 engine in their car. We are talking about 2x s54 engines with zero tracktime and 3x s54 that do trackdays.