I built a pretty large DIY sliding gate a couple of years ago. I did tons of research, but it was a very fun build and I'm still very happy with how it turned out. Here's a link to my build thread, which includes some lessons learned on the gate on page 2 and opener on page 3:
Rolling Driveway GateMost contractors use Eagle operators here. I was not impressed - they're loud and I've seen a few of them fail. After looking at several units in the field, I went with a Liftmaster. Their bigger units seem to be pretty nice, and my operator is much quieter, faster, and more feature-packed than those around me. I also like the commonality with my garage door openers, and the app support. The battery in my unit will let it run if there's an outage, but it also has solar panel options (still just powers the battery).
My two cents, the gate design is just as important as the operator. A bad design will lead to early operator failure. I drove around and looked at a lot of gates before I finalized my design, and started to notice some commonalities. A - some contractors like to use a side rail for the rollers to hold up the gate. They are often welded to the gate frames with 2" welds every 8 feet or so. Those 2" welds start to fatigue and fail early, which leads to the frame also bending/fatiguing. It's a good design on paper because it adds some lateral bracing, but crap in reality because of the welds. A 40' gate dependent on a 2" weld is going to fail in windy areas because the wind makes for a lot of torque on a gate that big. B - a lot of contractors don't follow the opener spacing requirements, and it leads to mis-alignment, or dragging wood when it rains and swells, etc. It'd be good to be familiar with these requirements.
