Just a backing up of what Jingles said.
Before I get onto that, sometimes it takes a few days to get a reply sometimes. Patience is a virtue. If patience isn't a virtue, there's phone numbers.
Pretty much most moving header/scanner units use some sort of stepper motors. The price of the fixture will tell you things like "how smooth" it will go, with higher price meaning smoother movement. Speed can usually be controlled via another controller in the same fixture IF the fixture has that sort of functionality. Most of the more expensive ones do since people expect more out of those type of lights.
Club-type lights differ from show-type lights. First off, price, unless it's a high-end club(which would use show lights). In most clubs, lights are just "icing on the cake" since most are there for the booze, atmosphere and hoping to score while not inheriting some STD. While lights are important, they aren't a focus and nobody is going to complain that the stepper motors do quick and jerky movements.
Now, I have a moving head fixture, and I can alter how fast it performs movements via a controller, going from fast to slow, in addition to controlling all aspects of it's movement, such as I can always move it slower than the fixture will allow me to move it, but if I don't have that speed setting cranked and I need to zip from A to B fast, I might not be super happy.
My advise: Spend more. It grows with you. BUT, if you're primarily doing smaller jobs, heck, save the money going with the cheaper fixtures. Your audience won't notice the "lack of features" and will still enjoy the lights.
When it comes to those I directly compete with, their idea of a light show is 4 par 64's or 56's on each side of the stage running a random pattern off a relay pack(1 pack per bank of 4). My idea of a light show has specials and a controller and actual control. I'm more picky than my clients.
Figure out who you ultimately want to please. In my case, I'm selfish: me. My audiences don't really appreciate anything, so I'll do a good job and let them benefit even if they don't say anything. Chances are, if you're picky, please yourself and your audience will love you. Please them and they'll still love it too but therse so many other factors to keep in mind.
Remember, you're in this for the money. Act like it.
(I say this after just spending $13K on new gear, after already having spent over $250K on new gear in the past 10 years)