The BMW guy was telling you some truths with a bit of brand loyalty thrown in for good measure.
Silicone hoses last longer and are cheaper than original parts. They are also more able to resist the boost pressure without ballooning. The OE rubber hoses visibly balloon when under boost, even when new. Now hoses swelling slightly under boost doesn't actually affect the boost ratio (pressure), one little bit. However as the turbo begins to boost the intake. Some boost delay is added because the of the ballooning, increasing intake volume slightly. It a small delay, but it's there.
The EGR delete is an interesting argument.
Fitting a delete kit does a couple of things to the engine.
First off it stops any further fouling of the inlet manifold, ports and valves.
Secondly it eliminates the problem of a sticking EGR valve, simply because it's not there to stick.
Thirdly. Removing the EGR improves throttle response, simply because there's no half air, half CO2 in the inlet manifold.
Exhaust gas recirculation was only ever added to the engine to reduce NOX emissions under some operating conditions. The idea is simple. NOX is produced when fuel and air (mostly Nitrogen) are burned at high temperatures. Diesel engines burn fuel at very high temperatures, simply by design.
Adding a non combustible gas (CO2 in exhaust gasses) to the intake, reduces the combustion temperature enough to reduce NOX.
The theory is sound and well proven to work.
However the exhaust gasses from a turbo diesel are far from pure CO2. In fact they contain lots of compounds which aren't helpful to the process. Soot is the main constituent of the exhaust gas. This is what the inlet manifold fills with over time. The sticky component comes from the boosted air charge, in the form of oil. This oil is ejected from the turbo as a fine mist. It combines with the heated soot to make the gloopy tar type stuff that clogs the manifold and inlet tract.
So removing the exhaust gas, keeps the engine running cleaner without having to clean the manifold every few thousand miles.
The BMW version of the M47 was a reliable engine. The M47R (R stands for Rover derivative) is a slightly different beastly altogether. The BMW M47 has a steel crankshaft the "R" 47 has a cheaper forged iron crank. These can and do break on occasion.
The injectors system is also different, the R having a bosch common rail system. BMW 47s used a more conventional sequential electro/ mechanical injection system. This is inherently more reliable than the more complex common rail system.
There are other more minor differences between the different engines, but those are the important ones.
Personally I'm not a fan of anything BMW.
I think the L series could have continued to be a more reliable power unit for the Freelander, right up to its replacement by the FL2.