If I understand you correctly (WJP) for character creation you use either the LBB 4 style or CT style with the addition of special duty and success (?) of greater 4+?
I typically use Basic CharGen, with the Special Duty and 4+ Success rules, yes. I run a CT game.
I'm also big on modding CharGen. It's important not to enforce the Surival Rule (make your players start over with a character if they fail a survival rule), the Optional Surivival Rule (make your players cease character generation as soon as they fail a survival throw), the Experience Limit (that no character can have a total number of skill levels that exceeds the sum of his INT + EDU), and the Maximum Terms Rule (Even if a player gets really lucky and makes all his Surival Throws, that total number of terms cannot exceed 7 terms unless boxcars are thrown on re-enlistment).
Enforcing those rules will ensure you don't unbalance your game. There's a discussion about this in the Classic Traveller forum. You should persuse that.
But...
Also check out the document in my sig. There's many ideas in there that will unbalance your game, but there's also many ideas on how to mod your game without unbalancing it too. Many people have found that to be good reading when starting a Traveller game.
I had had the impression that special duty and the success roll was used with the advancedchar generator.
Nope. The Special Duty roll and the 4+ success rule are strictly for the Basic CharGen types (the 4-year terms). This rule equalizes Basic characters with Advanced characters.
I'd forgotten that sensors etc were added in the design rules. I jumped over to the starship design topic and read that.
There are some rules for sensors in CT too. DGPs
GRAND SURVEY presented rules for sensors in CT.
Here's a thread about those sensor rules:
http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=10994&highlight=sensor
Note, though, that many people today argue that sensor rules are usless in Traveller because technology would allow for all combatants to see each other waaaaayyy before either got into firing range. So, the CT style of "no rules for sensors" is acutally more realistic (if you listen to that argument...and it's a pretty strong argument).
Check out this thread for additional information on other Sensor rules written for use with CT (and you might want to look at that whole thread, because it's got a lot of good stuff in it):
http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=11055&highlight=Index+Thread&page=11
Also, many people don't know that the LBB's had a 1st edition. What we think of as the LBB's today is really the revised edition. 1st edition Traveller actually had some sensor rules.
Here is a thread about 1st edition sensor rules:
http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=11077&highlight=Sensors
Finally, if you want some simple, easy-to-use sensor rules for your game, yet you crave some detail to go along with those simple rules, you can check out these sensor rules that I wrote just a few months ago.
The rules are very simple, but there's a lot of verbage there in the thread (I was trying to provide a lot of information about sensors for role playing purposes. A GM can play with as much, or as little of, that detail as he sees fit).
Here's the linky for those rules:
http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=11103&highlight=Sensors