You might want to check this link as well as the forums on this site for more information and discussion about this issue:
http://xoops-tips.com/news-article.storyid-62.htm.
Things you might want to keep in mind:
1) Does the hack require modification to core files?
2) How much work will you have to do, if any, to make it work with the modules you chooose to use? Is it a matter of making changes to the .htaccess file or are the changes more extensive tahn that?
3) How hard will it be and what will the penalty be to your site (in terms of search engine placement, etc) if you choose to revert back to the old url format? Its fairly easy to initiate "simple urls"; In terms of search engine placement, depending upon how long you use these urls, you might be much more seriously affected.
4) How will you handle XOOPS upgrades and security fixes in the possible absence of updates to the url hacks (though some of these hacks seem very well supported)?
5) What are the implications of the new 2.2 for your use and adaptation of the hacks? I think 2.2 is/will be a much more stable platform with many important features as it comes on-line. HOw easy/hard it is to adapt these hacks seems an unanswered question.
6) Does the anticipated benefit justify these changes? Why are you considering using this approach? Site visibility in the search engines? The value of "simple urls" in search engine ranking/placement is much debated, and in some corners quite hotly. You have to read up and make your own decision on this based on the evidence. Some time ago, the case seemed more open and shut for the value of "simple urls". Now, it is a little more less clear, based upon my impressions.
In any case, I think you're smart to do your research. I would make sure you search the forums here heavily. Don't depend on you're posting of this thread for adequate feedback on the topic. Personally, I like "simple urls" (making a reference her to style of urls, not the name of a particular hack). I hope that such an approach might one day be fully integrated into xoops.
But, having tried both hacks, I concluded that there was not enough gain in site visibility, and some modules simply did not seem to work with the hacks. I had neither the time nor the expertise to make the adaptations necessary to make those modules work. Having said that, I believe both modules have had some development since that time.
Of course, all this may be a load of crap. And, I am not certainly an expert on this stuff.