I've gotten 5000 a few times.
I have to disagree about the imbalance. The complete impossibility is what makes Rogue fun. When there's no reasonable expectation of winning, losing a good game is an accomplishment instead of an annoyance. You focus on how far you got instead of your failure.
I second that - I completely disagree on the imbalance.
The deal is - you simply have to plan and\or take risks.
Save your stuff so that you can try it when it's "safe".
Haven't seen a blindness potion? Then keep a see invisible or healing potion on hand just in case you get one.
Haven't seen enrage monster scroll? Then read scrolls after you've cleared the level.
In other words, if you always gamble, you'll lose a good deal of the time. Instead, if you manage the risks, you'll come out ahead most of the time.
As for "complete impossibility" of winning, I completely disagree again.
What makes Rogue fun (and unique) is that you CAN win! It's essentially an ASCII video game - the critters keep getting harder, but you can actually win it! I've won it twice this year, so it can be done. Trust me, when you finally DO win after countless games of trying, it's great! Our college CS lab (in the 80s) practically declared a holiday when the game was defeated for the first time!