That's a tough choice, and congrats on getting closer to sealing the deal. I personally went with the HSE (non-lux) because I'm actually going to use my Lanny (adventure!) and was worried the smooth leather seats would get destroyed by me and my 19-month-old son. I also LOVE the textured leather feel and look because it's fitted very tightly with no ripples (pleats) and coming from a family with Disco IIs the leather is very traditional Lanny all the way, whereas the Lux-leather is tucked in the corners with those "ripples" to give that particular customer that "luxury" Lexus-look-and-feel which I personally don't care for. I don't even think the Range Rover premium leather seats have that pleated-look... Plus, those ripples over time (less than a year) will get flattened and worn looking. Just look at used Porsches, where the seats were ordered with that option... they look like hell after a year or two. I wanted something where if the seats get wet I'm not going to have a conniption.
I didn't listen to the L7 system, but coming from a 2008 M3 with a 3800 stereo (which sucked IMO), I was shocked out how outstanding the HSE (non-Lux, non-L7) standard system is - I was absolutely shocked at how great it sounds. It blows away my M3 stereo, seriously! And another thing about my M3, the seats were impossible to keep nice, superbly wonderful leather, but not realistic at all for human beings. They were nice to look at... otherwise, useless. I can't be **** about stuff like that anymore... being a Dad has really changed my priorities. Anyway, if the regular sound system sounds great, then my assumption is the L7 must be mind-blowing. I did own a 2007 e92 335i with L7 and remember it was awesome. As for the Lux, well... that's a great price they are offering you, and it comes with just about everything one could want, and if you want top-of-the-line, then go for that one. The off-set is SO LITTLE. And if you want top-of-the-line and do not get the Lux, you might regret it later.
My reasoning was purely based on having less electronics and keeping it simple and using my Lanny for what it was intended to be. Less "stuff" to break and honestly, any car loaded with those types of techie complexities, will be a nightmare to own outside of warranty. One major reason for getting rid of the M3, I don't even want to think about how costly that car will be in a 1.5-years when it falls out of warranty. It was tech-city. I was absolutely determined to get the HSE non-Lux and went in with that mind-set no matter what. But if your mindset is determined on the Lux, you better get that one because that's where your heart lies. And remember, Non-HSE, HSE, or Lux, the LR4 is truly amazing regardless of options!!! I couldn't be happier with the brand.
Best of luck to you! And be sure to tell us which one you purchase.