There's a pretty big difference between driving a slow car fast and an Elise. Because it's not high in torque, most people used to large engines feel that it's not a fast car, but if you drive it as you should, which is over 5000RPM, this is a FAST car. It's not a Ferrari, but it's going to be faster than most anything else you're driving next to.
I usually agree with Jason (like the V8 Vantage is the WAYYY underrated, see his V12 Vantage video) but on working on the Elise, I totally disagree. Aside from the aero panels having to be removed for most work, which isn't a big deal at all, this is a pretty easy car to work on for regular maintenance. And the chassis/suspension are super simple. Very, very easy to work on. I think the biggest risk to owning the car is its delicacy. The fiberglass body is a tap away from being totaled.
I also own a Miata. Mine's a 1st gen but I've driven an ND, there's not much difference except the ND has no steering feel. The difference between the two cars is basically everything. The entire experience is completely different. I love my Miata, but it's a toy that you can drive anywhere without thinking about it. You can also drive it like you hate it and you're still not breaking any laws. It truly is a slow car fast, but it's the right slow car.
You will have plenty of opportunity to buy a Miata and if you want a used ND, you'll want to wait until the 2019 is a couple years old anyway. The Lotus is an experience, a truly unique one that you should have if you love sports cars.
I have owned many RX-7's (of all three generations) so I am comfortable with driving in the high rev ranges with less torque. I have driven an Elise for all of about 5-10 minutes and it was not on a track, but I have not forgotten the experience.
I get what you are saying about a Miata vs an Elise they are different animals, but they are still both very lightweight (Elise being lighter) RWD cars with the Elise being more driver focused (epscially in terms of steering feel). I have a long torso and just don't fit very well at all in the NB Miata but fit fine in an NC (ND won't be an issue).
I need to drive these cars back to back. The Lotus will be a more special car and more exotic, but also have the challenges of being a 15+ year old car that is harder to find people to work on and source parts. The Miata will be under warranty and I won't worry nearly as much about driving it. But I get it, the Lotus will be a more driver focused experience.
Need to drive them both back to back and weigh pros and cons. I need to research more on maintenance on these Elises as I seem to get different stories talking to different people from "they are easy to work on you can do the work yourself" to "these things are very fragile and you will spend many weekends just doing routine work".
I have three active kids and can't really give up whole weekends to wrench on cars in this stage of my life and I don't want a $35K paper weight and miss the optimal driving months because I am waiting on parts or someone to repair something, or I don't have time so the car sits.
I am sure I am thinking worst case, it's also likely I will have a car that has minimal issues and I may enjoy working on the car.
I clearly need to research and ask more questions when it comes to maintenance.