If you have a decent shop vac w/ a filter for drywall/fine particulates dusts, you might consider a pole sander w/ a vac attachement. Lot less money!

Here is a link that might be useful: dustless sanders

I have tried manual sanders which attach to a shop vac. I have found the vacuum suction on the sander head holds it like glue to the wall, requiring great effort to move it around. I was hoping the motor on the Porter Cable would take care of this problem.

I hate renting tools, but the pc sander is around 1k. Im sure you could knock it out in one day renting one. Otoh, if you have future projects, it could come in real handy and nice tools make the job go smoother. Tough call. Sorry, no experience w/ the pc, but i have heard they are nice. As far as getting used to it and not digging in, practice on a sheet up against the wall until you get the feel of it. Like most sanders, you let the sander do the work only applying slight pressure. Good luck!

I have used the PC sander on 3 different occasions. DEFINITELY Worth renting. Sanding by hand takes forever - as good as the idea of a pole sander sounds and looks - it is not any fun. The PC sander makes short work of seam sanding. Buy a couple of sanding sponges to get the corners and you are all set. One note; when your vacuum gets full, drywall dust will start blowing out quickly - empty the vacuum and clean the filter often...

In my opinion every tool company has one tool that they make exceptionally well. For Porter Cable it's their orbital and drywall sanders. Those sanders are great for drywall because they are so light that it gives you a lot of control over the pressure your putting on whatever surface you're finishing. My favorite trick is to get a can of compressed air and spray off the wall as I'm sanding to get rid of the excess particles on the wall. It's a little messy on the floor but you will get a smooth finish and don't have to worry about the suction problems.

Here is a link that might be useful: eReplacementParts.com

If you need to sand the PC pole sander is about as good as you can find.

Unless you need it on a daily basis, renting is a good option.

There is a learning curve to the application of gypsum patching products and the sooner you learn the simple methods of application to virtually eliminate the need for extensive sanding, the simpler your life will become.
I sand very little, however, I've used the sander on numerous occasions because I often work at night in functioning offices, and need to limit my finish to prime and paint time.
The learning curve in the tool is in the selection of grit.
As mentioned, cleaning the filter and changing the internal collection bag are important.