Hi Darra, I hope you have found your answer. Welcome to the forum.
All that said, I thought you would like to know that what you read above is very far from infighting. We know each other very well (if only online) and tend to rib one another. Your question, being a very common one is pretty open for others to bring their opinion too. This topic, as discussed as it is, is one of those topics where there simply is no simple answer.
Everyone will give you an opinion. Procoach has a good point. Lotus put more time and effort into the tire selection, obviously with some encouragement from Yokohama, than any one of us is likely to ever do. So I second Procoach's opinion.
I wonder if you have checked out Tirerack.com or Treadzone.com (a sponsor here). I personally go to Treadzone for my tire needs first then tirerack second. You will find both sites informative but tirerack has a great deal more information to help you make a selection. Treadzone is a smaller company and you can call them directly and receive candid, professional advice.
You asked why Yoko has specific tires for the Elise and NSX. This is a common practice is many of the higher end sports cars. Lotus wanted a tire that (I'm speaking to my experience of 2 Lotus cars both with LSS suspension and wheels and thus AO48's) was stickier and lighter at a reasonable price point. They knew/know that people that buy these cars want a car that places performance over comfort at a reasonable price through a philosophy of Light weight. Thus the "LTS" designation on the AO48 in our sizes. These tires, if you look closely (AO48) have a higher traction rating and are slightly lighter than the AO48s without the "LTS" designation. This lower weight reduces unsprung rotational mass which is perhaps the most important weight to remove from a car when seeking performance.
So that post is probably a little long winded but I took the liberty, given your low post count, to assume you haven't been here too much. Hopefully that was a value add for you?
Best,
Trevor