If you buy the IATA-sized Rimowa, you will almost certainly not get hassled by LH. As Till said - LH has Rimowa make most of their house branded bags and it would be awful marketing to make people check those. Also, the price of Rimowa bags is likely to mean you are annoying someone who you want repeat business from. The only other way to get away from those ridiculous MEC rules is to go without wheels, which also seems to throw them off.