The first clippers that I had ever owned were Oster variable speeds and a set of Sunbeam flat heads. The Sunbeams were my fathers and I used them for well into my later teens (I am 24) and I purchased the Osters in 2001. I clip bull pens, sale cattle and every now and then show cattle with them to this day. I have replaced the chord a few times, lots of blades and sharpenings but the clippers sill work just fine.
Starting with big clippers was a huge advantage for me. I feel as comfortable with them as I do my Two Speeds or 5 Speed Andis. I will admit my father was a patient man and encouraged me to be proud of what I did on my own when i had first started clipping. I messed up a lot and still am not perfect. I clip a few still and travel around when I can. Big Clippers are not evil like some say, I use the Premier 4000s now and they are way lighter than any other large clipper I have used. When you make a mistake with big ones, it can be a big time mistake but it is no different than hitting skin with your Andis clippers, a gouge is a gouge. Never be scared to clip, its just hair. It grows back, the bull wont breed her because she has a gouge and the meat wont taste any different. If a judge cant look past a gouge they have some serious issues. I leave a sizable hole in one every now and then, heck people need to know who clipped, hahaha.
IMO Big clippers last much longer and it is beneficial to be able to take them apart, clean and re assemble. I reallyl like my little clippers for when the arm gets tired, really fine tuning or stall clipping. it is all personal use and preference, i just wanted to say don't be afraid of using big clippers. They have a bad rep for no good reason. If you ever want to travel and clip sale cattle, bull pens or anything along that line your best friend will be Osters, a true skip tooth comb and a torch.