If I were buying an almost new used luxury car like a Lexus I wouldn't consider a car that hadn't a proper franchise history.
I think that if you are putting a big wad of cash into such a vehicle then surely it is worth getting it maintained by the franchise for the inside product knowledge they have access to .
A prime recent personal example is a lady I know bought a Ford cmax from the main dealer. Being too tight to get it serviced by them it was entrusted to a local garage This garage were unaware of the eco boost engine issues. If the car had been Ford serviced they would as a matter of course have followed a service bulletin and replace a suspect pipe. The car was never modified, dumped its coolent in 2 seconds and wrecked the engine. Cost the lady thousands of pounds to replace the engine and then much grief to try and recoup some of the cost. I don't know if she succeeded or not but the car was sold shortly afterwards.