I'm using H&R - but I was lucky as I pick them up used.
Your quoted price is not bad - with install it sound pretty good - as they are only charging $ 500.00. My install only cost me $ 700.00 and that was the cheapest quote.
I can provide you with comments but they will not be accurate for the following reason:
1. I have a MCS
which use a SS+ suspension.
2. I have 18" wheels which I had installed before the spring.
1. Car corners much better with less lean.
2. Realise that the stock shocks are much softer when you don't have runflats. There's not enough dampering .
3. Good ride height - but my front lip below the spoiler keeps scratching on steep areas.
4. Ride quality is o.k. pretty comfortable.
5. With a full car of people the springs do go down another .75" - 1" in the back.
I have not tried the Eibach - but they were my first choice. Heard some good comments about them.
Eventually i'll go to a coilover system as i'm not too happy with the standard shocks.
Hope this helps.