The subject of declawing cats is an extremely opinionated one. It's kind of like the saying that you don't discuss religion and politics with friends...well, you don't discuss declawing either!!!!

As you can see there are many different views and opinoins and this is something that you will just have to decide on your own.
I'm a veterinary assistant, working on getting my vet tech degree, and in my field I am among the minority that don't have a problem with front-paw only declaws. I assist in these procedures and I watch the cats as they are waking up. The way my boss does it the nail is cut at the joint where it is connected to the toe bone. They spend the night in our clinic with their feet wrapped, we take off the wrappings the next morning before they go home. Yes, their feet are tender for a short time, but in the 2 yrs I've been here I have never seen any cat in excruciating pain. Besides, we can't measure an animal's pain based on our perception. Talk to someone who has had an hysterectomy and more then likely you'll hear that they were laid up for at least a few weeks. I know my mom had a hard time getting around for about 2 months. Now, a dog that has gone through the same procedure, is up and walking around with tail wagging the very next day and that is without pain medications. Granted they are sore, which is okay because it keeps them from doing something stupid and slipping stitches, but for the most part they are up and doing things as normal less than 24 hours after the surgery.
If it's an outdoor kitty I wouldn't recommend getting the declaw done. But even a front-paw declaw does not render the cat defenseless. They still have the rear claws and their teeth. If you watch a cat that is fighting they tend to wrap their paws around their advesary while scratching with the back feet and biting. Even without claws in the front they can still hang on and defend themselves. I think somewhere else I've heard the argument that at one point or another all indoor cats escape....None of my cats have ever escaped! You just got to keep an eye on them and mine have been taught to stay away from the doors.
I have also had cats my whole life and only one of our indoor cats was not declawed, but he was an exceptional kitty. I have never had a problem with any of my cats, psychological or otherwise. If you are home 24/7 and can keep a constant eye on your cat, then there are those that could possibly be trained...but it's not easy to untrain something that is just nature to the cat. And all cats are independant enough that when you are not home, they are going to do what they want to do!
Even clipped claws can still scratch and after a period of time they will leave marks on woodwork as well. The nail caps are an option, but if you plan on using them on an older cat, be prepared for a struggle! They are applied with superglue and the majority of cats that I know, even kittens, aren't going to sit still very well for that. I also know that economically, they don't work out. Where I live you get a pack for $24.00 and at the most there is only 2 applications in a pack. We only charge $45 for a front-paw declaw, so depending on how quickly your cat's nails grow you could easily spend twice that on the nail caps in one year.
The way I see it, for alot of people the decision is declaw the cat or get rid of it. The last thing we need is more cats thrown outside or placed in the shelters. It's a way of saving the cat's life to continue offering this service.
That's my opinion and my experience. It's a decision that only you can make, I would def recommend talking to your vet about it and see how they feel. Ultimately, only you can decide what is best for your cat and your situation.