Hear, here!
I've gone through multiple pairs of non-custom plugs that are more balanced than foam plugs, but currently need another set. Always good to have extra foam ones on hand just in case and nice to have extras for others. Of the foam plugs, I find the classic yellow barrel-shaped ones to sound more balanced than the bullet shaped ones when used as I mention below. Its not only the shape, the foam material they are made from is different as well.
A few tips on using standard foam plugs, and a good option for when you have none available but need hearing protection-
● Standard foam plugs work much, much better in the perceptual sense if you put them in well before it gets loud. Your brain then has time to adjust to fully adjust to the change. Then once the music starts it will sound much more natural and considerably less muffled. If you wait to put them in until after the music has started and you find yourself thinking "its loud, I should put ear-plugs in", its too late in terms of achieving a more balanced perception of the sound. The opposite occurs since your hearing mechanism has already taken what precautions it has available to it when subjected to high SPLs and your brain has already accustomed itself to those high energy levels and frequency balance as being "correct" so that insertion of the ear-plugs at that point will cause everything to sound far more muffled. But do it anyway as its never too late in terms of protecting your hearing!
● I often put them in as audience is arriving and the ambient sound level starts increasing. Once adjusted to the sound I have no problem hearing conversations before the music starts. The most difficult part is talking to other folks at an appropriate level. It can be difficult to judge how loud to speak, so its easy to either end up speaking too softly to be heard, or realizing that, over-compensating and talking too loudly. If you do this and take them out to check or talk more intimately with someone, its is amazing to realize how loud the room becomes before the music even starts.
● Unless very little protection is needed, I find the foam plugs work best, both in terms of protection and in terms of achieving a more balanced frequency perception when fully inserted so that the outside edge is flush with my ear opening and the plug is axially compressed along its full length as well as radially compressed withing the ear-canal. That maximizes low frequency attenuation with a good seal, while attenuating high frequencies somewhat less than they will be if some uncompressed plug is left hanging outside of the ear-canal. The response is flatter that way. Can sometimes be a challenge to dig them back out though.
● If no plugs are available, a method that is somewhat gross, yet works nearly as well is to grab a cocktail napkin or some other piece of paper or light cardboard. Rip off a square and chew it up good into pulp, then form that into plug and use it like you would a foam one. The chewing mashes the fibers and the saliva holds it together, creates a far better seal, aids insertion, and makes wearing them more comfortable. If this grosses you out, try it to see how well it works and you may well get over it. Do it discretely and one else needs to know.