Re: How much difference does the equipment make?

Yes. It does.

From a basic, banal standpoint: If you swing right, and I give you lefthanded clubs, you won't score well.

To go one step away from ridiculous; If I give you a 6° driver with a XXX flex shaft, how well do you think the average golfer would hit it (by average, I mean aggressive downswing at 90 MPH)

I can set you up with 2° open drivers, and watch you fight a slice all day. I can put a 5° closed driver in your hands, and watch you fight a hook. But if you figure out how to compensate, you'll hit moon balls - as the effective loft will be 5° higher than whatever the loft is.

Lets take another scenario - a little less drastic, a lot less likely (to the degree I'm about to showcase, but it's certainly there):

Take your iron set. They're set for, lets say, 4° loft gaps from the factory. The tolerance is +/- 2° for loft. So, if the 3 iron is 2° weak, and the 4 iron is 2° strong, then you have two clubs that go the same distance. Lets do the same for the 5 and 6 - weak and strong respectively. Now, not only do they hit the same distance, but you have a 2 club difference between your 4 and 5 - 20 yards for the sake of an argument.

How about hitting a belly putter when you're used to a 32"? Or a broomhandle? Any clubs that are too short or too tall for that matter? Sure, you can learn to hit them, but are you going to be as effective as having equipment that fits you properly?

Re: How much difference does the equipment make?

How do you know if you are playing the appropriate flex of shafts? I am currently playing stiff shafts in both my irons and woods. I was told by a pro who gave me a playing lesson that due to my swing speed and my strength (even though I have a smooth swing) to stick with stiff shafts.
He said a regular flex will increase my trajectory and decrease my distance. When looking at irons another pro said I can go either way.

Any suggestions on what type of shaft to buy with a new set or irons?

Re: How much difference does the equipment make?

IMO, there are two ways to go about it: Trial and error (my preferred, but I'm a club ho), or getting your numbers down in a launch monitor (or hitting ton's of demos from a clubfitter shop).

Without seeing your swing, or knowing your swing speed, I cannot make a suggestion as to a shaft that may benefit you.