I think open space point -> point ftl should really be only mid-sized ships. Small fighters should lack the power to FTL and titans should simply be too massive to FTL.
While I'm guessing people will understand why I limit fighters but why titans?
Titans are big. Titans are well armed. And overall VERY dangerous ships you don't want a titan suddenly appearing in a sector spreading confusion and lag, this is kind of extended to larger combat ships as well. You don't want something big and dangerous to be overly mobile.
However this is why portals / jump gates are a form of travel I support. If you want to get that titan across the map in record time be prepared to work and leave yourself at risk getting that gate up. Send engineers ahead to construct the superstructure and get some more mobile ships to keep the enemy occupied elsewhere, get though and lose your gate? Shame, you should have been more careful, now you are stranded and left to die.
Game needs more risk v.s reward. Not more "lol jump in and trash their base and smash my pretty ship into that big base."
Again modifiability rules the day. If you want ftl to limit more or less ships then make it so in server config.
I disagree with FTL requiring super specialized ships, FTL should require you to have to think about it as part of the ship hell I'd even have it drain energy even what not in use (to an extent), greater mobility = greater liability. Of course building specialized FTL ships to courier specialised short range warships (movement range) and fighters should be possible and maybe encouraged for the sake of teamwork but by no means necessary.
TLDR:
Types of FTL discussed - Jumpgate/portals and point->point
Points made - Mid sized ships FTL only, no titans, no fighters and maybe limit some larger ships. Balance using energy.