That's a tough question. Obviously, it's always best to keep your domain name as short as possible, and domain names beyond 25-30 characters are probably too long to be practical.
From a business perspective, the fewer obstacles you put between your customers and your business, the better off you'll be. For instance, if I receive an e-mail containing a mistyped url (because the sender misremembered the long domain name), I might just blow it off and move on. Also, in your specific case, there are quite a few companies with the name "Nexus Technologies" so you may not want people to have to search for that name (unless you're ranked #1 on Google for that term).
That said however, I think nexustechnologiesllc.com is right within the borderline of acceptability. It's long, but not hard to remember. You might want to see if you can grab nexustechnologylcc.com or buy nexus-llc.com or nexusllc.net (both currently available) to make things a little easier for customers, but I wouldn't worry too much about it otherwise.
I would NOT buy a domain name from a domain squatter/prospector/resellers/etc. Remember, they're the reason we're running out of good domain names, and probably the reason you needed to add llc to your domain name. In fact, both nexusllc.com and nexustechnologies.com are owned by squatters/resellers. So buying domains from them for hundreds of dollars is like clicking on spam and encouraging more spam. Just don't do it.
