Best 5.1 options under $5k

The greatest impact by far will be to go with 2 speakers and stereo. If you really care about sound quality $5k will buy a lot with 2ch, or as many channels as you want, but nowhere near as good quality. Your best 5.1 option is 2.0. I spent more than a year trying all the options. This is the best I've been able to come up with.  https://systems.audiogon.com/systems/8367

I think looking at SVS is an excellent idea.  They offer very good performance and value along with outstanding customer service, and their center speaker (crucial for good HT) is superior at the price point IMHO.  If this is strictly for home theater, you could get the SVS Prime Tower surround package with SB2000 Pro sub for $2315 and add an Anthem MRX540 AVR for $1600 and have a damn good complete HT system for $3915.  Just make sure to add some decent cables (Cullen Cable, etc.) that won’t compromise the performance and you’re done.  Best of luck. 

In my opinion, the SVS are okay but they are not the greatest resolution speaker.  The best speakers I know of in this budget level are the Elac Debut Reference (DFR52, DCR52, DBR62).  The SVS will sound a little dull in comparison to the Elac Reference.

The SVS subwoofers are really good for the money, but I think they have a characteristic sound.  This type of sound is very popular among the consumer electroncs crowd.  In my opinion, Rythmik Audio makes a better subwoofer that is more neutral and realistic in the bass tones.  You will most likely be happy with either.  That being said, I always recommend getting a ported sub for home theater purposes (as opposed to a sealed sub).

SVS is decent, but there are better... I don't agree with a ported sub, you want something that is great for everything. DC servo, push-pull is my first choice. Sealed or subs with one passive drivers are good too.

It is a taste thing.  Sealed subs generally sound more clean, but they do have somewhat of an artificial sound to them (a very slight slant) where it almost sounds like a sine wave. 

Ported subs, on the other hand, sound thicker and meatier.  In my opinion, ported subs just sound better.  There is an argument that ported subs create distortion (which could be true).