First of all, welcome to RennTech :welcome:
I continue to be amazed at the inconsistent and often totally incorrect information being passed around as "fact".
With a quick search, you can turn up more information on the true level of problem the IMS caused. Porsche recently settled a class action lawsuit which revealed that at its peak, IMS failures occurred in around 10% of the engines made during the time frame covered in the legal action. As for cylinder liner scoring, yes, that also occurs, but has not proven to be as widespread or as catastrophic as the IMS issue. When you have an engine start scoring a liner, it may go down on power slightly, or consume some oil, but it still runs. When the IMS fails, the result is instantaneous death for the engine:
So when liner scoring occurs, you still have a running engine than can be repaired; when the IMS fails, you have a $20K boat anchor where your engine used to be.
As for alternative replacement bearings, consider that LN has more than 12,000 successful retrofits on the road; how many does this other company have? After Charles Navarro and Jake Raby developed and perfected the retrofit procedure back in 2008, a lot of other companies jumped on the band wagon with their own "copy" kits. Some are still around, others have been less successful, and their customer's ultimately "paid the price" for their lack of understanding and basic research into what works and what does not when it comes to IMS bearings. There have actually been cases where some of these alternatives replaced a still fully functional factory IMS bearing, only to lead to pictures like those above, and the disappearance of the alternative supplier from the market. So I would be very cautious when someone tells you that they have a cheaper alternative to the LN products that "are just as good". The LN product is not an "off the shelf" unit, their bearings are made for them, and every component selected for their bearings has been tested to destruction to get the greatest durability and life expectancy.
As for LN being sued, I am not aware of any case against them. Over the years since the retrofit was introduced, there have been some dozen or so cases of LN IMS bearing failures, most of which were traced to improper installation techniques, or the LN bearing being installed into an engine that was already dying and full of metal shards which ultimately got into the new bearing. Both Charles and Jake have been very forthcoming and open about these instances, and I am sure they would quickly respond to your inquiry concerning this question. Both have websites of their own (Charles is at http://lnengineering.com/, Jake at http://flat6innovations.com/ ), and both regularly appear here as well in response to questions about these products and competitor's claim's.
As for "waterless coolant", I'm not all that sure about that either; the product strikes me as a solution looking for a problem to solve. We see literally dozens of liquid cooled Porsches every day in the shop, some with over 200K miles on them, and not one of them are using this "magic ingredient" as you describe it, and none of them are dying from liner scoring.
To go back to your original question about your oil leak between the transmission and engine cases, it could be either the RMS or the IMS; both are well known to leak. But if you have a leak in that area, it is not going to get better, and things could get considerably worse if it is not addressed. Regardless of where the oil is coming from, over time it is going to both ruin you clutch and potentially degrade the elastomer in your dual mass flywheel. While the pressure plate and disc are relatively cheap by comparison, the flywheel is not and could easily set you back the better part of $1K (US) just to buy it. On the other hand, if you took the car apart now and repaired the leak(s), you could still be able to salvage your current flywheel; and you would have the opportunity to retrofit you IMS at the same time, ending all of your concerns in one move. Just a thought.............