I have been a Logos user since Logos 3 (for Mac, which was just plain awful - I regretted that purchase). I then got Logos 4 and then Logos 5. Each edition of the product was completely buggy and unfinished when I initially purchased it. It then got better over time to the point where it was more usable. Even on its best days, Logos is very slow and is a resource hog.
So, I waited until Logos 6 was more mature to upgrade to Reformed Diamond. I also waited until I enrolled in Seminary to get the Academic Discount. I very much have been enjoying my Logos experience for the first time immediately after purchasing it. I don't know if Logos 6 was more bullet proof at launch than the other versions, but so far Logos 6 has been far speedier and less buggy than the other editions were when I first bought it.
I am currently running Logos 6 on my Surface Book (Dual Core i7 Skylake with 8GB of RAM). Logos 5 seemed laggier even on my Quad Core i7, so I think they've made improvements under the hood. The indexer seems far quicker, though maybe my SSD is faster in the Surface Book than the SSD was in my old Lenovo.
Just a note - I make sure to not launch Logos 6 to their "homepage", because what inevitably happens is that it ends up being an advertisement for more of their products (these you can filter out), or worse you find out that some broadly evangelical resources that they pull an article out of has the inevitable 2nd Commandment violation and suddenly you have a picture of "Jesus" staring at you when you want to study God's Word. I have mine launch straight to my saved layout to save me the grief.
All that said - Logos is very pricey, especially to get a package that you really want. Most of the resources that I care for are all in the public domain. So why do I use it? It saves me a lot of time. And for me, time is a very precious commodity. More precious than money at the moment with a family of six, three demanding clients at work, duties as a ruling elder, and now as a seminarian.
It is easy to cross reference works, it allows me to do Bible Studies effectively, and even a feature as seemingly trivial as being able to see the Scripture proofs by hovering over them in a resource is a tremendous blessing and saves a LOT of time over the time I've used it.