CR90 more survivable? meh.
Just like the raider, if the CR90 gets the love and attention of the big boys it melts.
I don't run my ISDII without either XI7s or HTs so one good long range double arc roll with CF and it can severely inconvenience or destroy a CR90, if it's a B trying to get smart in medium range...well....
You can't expect a raider to survive much more than a CR90 and quite possibly less, it has the ability to hit quite hard and the tradeoff is it dies.
I'm no expert but I find raider works best when you give the opponent the difficult choice of melting the raider or hitting something bigger, to that end I find on a big slow list you HAVE to keep the raider close to your big boys and dart them out like a dagger to the gut at just the right time (and ANY DAY NOW I will learn how to do that right...lol) on a high activation list I have seen the little bastards do very very well swarming with ACMs and screed, speed 3 or 4 and ram or fly-through follow up with demolisher and generic glad, maybe a mini fireball.
It's not a perfect ship, perfect ship would be game breaking and actually kinda boring. It IS however, a necessary fast, small base option to fill a particular tactical need in Imperial lists for which there was previously no solution.