It might not always matter in terms of stability. Often the run has more to do with determining that. I have lighter discs of the same mold in my bag that are more overstable than their heavier counterparts.
What DOES matter is that most people can swing their arm around faster with a lighter disc. This often translates into the disc being less stable than a disc that is heavier. Heavier discs are not more overstable, but if you can't throw em as hard and fast as a lighter disc of the same mold, that is the net effect.
Does the 3-5 g matter? Only if it matters to you. The difference may not be even noticeable. Try blind throwing a 170g disc and a 175g disc and try to guess which was which. If you can actually tell, then I guess it matters.
For me yes. I can generate more spin with my lighter drivers. I've thrown my 165g and 172g Valks side by side. I was able to hyzer flip and then get a helix out of the 165g, but the 172 just flattened out with no helix. This was repeated over an hour+ of practice and the results were consistent. I also feel that lighter is better with a tailwind. With a headwind as well as putting. I did not detect a differnce.
For your discs a few grams is irrelevant. If it were taken off the tip of your nose it would matter.
Most Pros throw max weight on everything because they are strong players and were taught that strong players throw max weight. So it is a cycle. If the Pros tested enough lighter discs they probably wouldn't care.
I threw max weight everything until I tested a bunch of discs for my sponsor. Now I don't care.
For me, weight is one of the most important factors in how over/under stable a disc is. For example, I can flip a 166 surge, but a 175 sidewinder only flipped flat. Same experience as rescue, but with completely different molds. I don't have a whole lot of wind where I play, so almost nothing in my bag (besides mids and putter) is max weight.
I like my drivers lighter...165-170 and my mids around 175 or so. After only playing a short time, I think that it is the run that makes the difference in stability. There is something to be said about throwing a lighter disc, more glide, better wind pen, and you can usually throw it further. I can't imagine a few grams "really" makes a difference...I think for a lot of people it is psychosomatic more than anything. I've thrown my 150 class Flick just as far as my nearly max weight one and they both went relatively the same distance. I'm sure a pro could definitely produce different results as their technique is much more near perfect than mine. I think for the average person 3-5 grams is negligible honestly.
I notice flight differences every 5 grams...
So for me, I throw 175, 170, and 165 gram discs.
The lower weights allow your wrist strength and snap to put more spin on the disc.
The heavier it is the slower your wrist strength will get it spinning.
Spin is what holds the disc in the air...more spin and it will stay in the air longer...the longer it stays in the air, the further it goes.
Lower your weights and adjust your angle of release and you will attain your maximum distance.
People with lower snap and less wrist and arm strength should stick to the lower weights.
People with a lot of snap and torque can use heavier weights and will "turn over" the lighter discs without adjusting the angle of release.
If you release the disc at an angle where the spin brings it up to flat (or a little past) then you will get some glide and distance.
There are other ways to do this...some people get new discs and throw with a ton of anhyzer to let the disc hyzer to flat and then glide.
Others use beat or flippy discs and throw them with hyzer knowing they are going to flip up to flat.
Field practice with your drivers will show you a lot more...get the same disc in three different weights and experiment.
That is what Dr. Alan Adler has to say about it and he is right!
I'd have to agree with Disc-O.
2-3 grams dont seem to make as much a difference as 5-7 grams does . for me anyways.
I try and stick with as few models as possible and try different weights within that mold and I like to think it's helped. my scores may or may not reflect that though,haha.
and I like what Mark said also. as I've gotten back into disc in the last few years I've had this mindset that heavier was better ( for my throwing style) but I've finally started to learn more of how weight will effect a throw.