Anyone who halves their speed to fight a serious threat is presenting a serious risk to their well being in exchange for a sizable experience gain. I use this tactic for my ultra games because gaining EXP in any other way is such a grueling experience that it will, in fact, become the hardest achievement in standard ADOM, surpassing the difficulty of the Ordinary Chaos God because of the level 45 requirement. Furthermore, it would make Ultras nigh-impossible with trolls, unless great care was taken into making it accessible to them.
I'm going to stay neutral. There's a fix to this, but unless it's explained in detail, I'm not for it.