Interesting. Could you elaborate on your two lessons?
1) No true solo fight with lurker / skirmisher: Meaning these combat types are not capable of making an enjoyable truly "solo" fight.
2) No clear shot: such as hit and run tactics from the solo?
First Part:
Well, Lurkers and Skirmishers.. to me, they play like rogues/rangers... how good is a rogue by itself? Ranger? With friends (even minions)?
No, they work best on capitalizing off of openings made by friends. The more resilient or numerous of these friends, the more openings that are made, the more damage your lurker/skirmisher solo can do... If it is by itself, hit n run tactics really don't work so well (unless some special move action ability is given, like an at-will teleport move action)
On the second part:
Try to make it so the solo and one or two people have good lines to each other, but no more, if you let an entire party get on your solo, it is dead. If you let the entire party ignore the solo, it is dead. This is unless you have a solo that you should not have thrown up against the party (a la 6th level flying blue dragons in a desert of no terrain lol vs 4th lvl party)
Instead, allow the solo and one or two players tango for a lil bit, if the going gets rough, make sure there is a get-away button, otherwise, go for it, let your chump mobs take care of the other players for a little while. Usually, you can drop the level of your solo by one (choose a different color dragon, unless you are absolutely in love with one type, like me lol) and gain enough XP budget to buy some friends to use.
In Any case, I try to avoid TPK's unless the group is completely dumb. If they have done things right, and all is going like it should, I will throw a Deus Ex Machina in there to save one or two party members to keep it from being completely horrific...