Sounds like a cheap thin hoop.  Get a new one.  At least 2.3mm "power" hoop.  Also, dont dismiss the diecast so quickly.   Sounds like it might be perfect for what you need.  Not just for durability but would add some meat to those rim shots and might make it more suitable to play off the rim as well.  Any minor differences in resonance can be fixed in tuning.

Ill assume you tried the diecast on your drum specifically?  Not to beat a dead horse, but if youre bending hoops you might need a compromise.  Either live with bent and bending hoops or rethink your tuning.  "Bright pinginess" can be brought down with head choice and tuning.  And steel shells being especially prone to that naturally, a little duct tape muffling in the shell would help that too.   It might be worth experimenting if it means having a hoop retain its shape and your drum stay in tune.

As for the "power" hoop, just ask for one the right size and number of holes and check it out.  Typically hoops are either the thinner 1.5mm or 2.3mm since theyre pretty much all World Max, theres not a lot of variety.  Bring in your old one and make sure the new ones heavier.  

Sonic differences between a thin hoop and a heavy one are  minimal if any.  One of the reasons die cast sound so much different than flanged is because of the way the its made (cast as opposed to stamped).  While the differences between a light and heavy flanged hoop is only weight.  I found that when I replaced some cheap hoops on a couple of my snares with good ones, they had a little more depth.  Not a pitch change as much as a more well rounded sound.  Clearer, cleaner sounding.

Die cast hoops are really the way to go, as they don't bend and the head gets seated in a uniform manner. They take the ultimate beating.

If you don't like the die cast, ask for a new triple-flange.

Triple-flange isn't as sturdy because it starts out as a straight piece of metal that is bent to fit the head.

If you must have triple-flange, buy lots of them because you'll tear 'em up if you hit hard.

A cheap thin hoop will not hold up to heavy hitting.  You will have to adjust your equipment!  A sound that is a little too pingy is a lot better than a sound that only last a minute or so.  You will have to make a compromise somewhere, either in your equipment or your technique.  

Check the roundness of the drum. If it's out of round, hoops will be prone to getting bent out of round fairly quickly.

thanks heaps for all the suggestions, but i went on instinct and got the flanged hoop instead, turns out that when premier made the drum i own they were in the habit of making their hoops a few mm too wide in diameter. the new hoop is working like a charm. sounds great, my snare lasted the entire gig last night without losing its tuning.

with regards to my technique, this could well still be a huge part of my problem. i dont think my technique is very good at all and my current financial position forbids me from getting lessons, so does anyone know of any resources either online or in book format that i could use to adjust the way i sit at and hit the drums?