I've never been overly fond of skill based systems, probably because I like class based ones so much. Class based systems are about the team; if the game system is designed correctly then no single class is a match for all challenges. This forces players to work together and becomes the spirit of the roleplaying experience - cooperation.
Skill based systems, on the other hand, are more about the opposite - the individual. Players will instinctively attempt to cover all bases when choosing skills, minimising their dependences on others and essentially making their character as independently powerful (as opposed to being powerful when operating as part of a group) as possible. Skills based systems are a good fit for single player or low player games I think.
Normally skill based systems are fairly balanced at the start of a characters career then go a bit haywire when a character hits the higher levels, so I've been avoiding using one in Labyrinth Lord. Until now. I've changed my mind because there is a side effect to skill based systems which can be quite desirable ... variety.
When the players roll up characters, ability scores alone are not enough to differentiate two characters of the same class. They can be roleplayed differently and a variety of equipment bought for each; but after you've done this a few times.. well a fighter is a fighter and isn't too different at level one than the next one. So now I'm thinking, lets bring a skill system into play.
One criticism of skill systems which I agree with also is that they can be exclusive. For example, if you make a riding a horse a skill, it tends to prohibit players from attempting to do it that don't have the skill and the rules may explicitly prevent this also. So skill systems can detract from the game experience for this reason, too.
I've been thinking of a way around this situation. Take my riding skill as an example. Say it was based on your dexterity attribute when you had to make a riding check. If the skill was rated in points, it could add to your dexterity score to make it more likely you pass the test. Characters without riding could still ride but would be relying on their natural dexterity (with no skill bonus) when tested, such as when jumping an obstacle on horseback. Clearly, this would still be inclusive - not exclusive - and provide a benefit to the skilled characters. I've not got it mechanically sorted out yet, but say you test on a d30, you could assign a +5 for a character with riding skill and allow it to develop still further as the character levels up and assigns skill points to improve it. I think this might work.