Reasons to use Antimatter Blade BR?

[Pavane]

The obvious reason is a speed vs. armour trade off. I haven't noticed that they survive any longer in battle, given that you will be well into the mid-game when these are cranked out of your shipyards, and the sacrifice if far more than armour. I put Blade engines on Interceptor BR's because their mission is to hunt and kill enemy BR, so I figure the speed advantage should allow them to better chase them down and bring the strafe guns to bear. I like Stealth Armour on my Scout BR's so Blade engines are out because they don't support it. Other than that, regular Antimatter engines seem to be the better choice.

To summarise, Antimatter Blade engines for Battle Riders, when compared to Antimatter engines, are:

• 150% more savings cost
• 50% more production cost
• 25% less power available
• 33% less supply available
• 32% better acceleration
• 16% faster speed
• 27% less base armour
• 20% less structure
• 39% greater mass
• No medium turret
• No Stealth armour option
• No Improved Reflective Coating option
• Greater range? (I assume the endurance is measured in seconds and that both engines are the same)

[Mecron]

you last point is fairly critical when speed translates to range over time.

[Pavane]

you last point is fairly critical when speed translates to range over time.

Yes, the Blade engine will have a 16% advantage in range (disregarding acceleration, and assuming both engines have same endurance). I am not sure if that is enough compensation.

[Mecron]

you've either tried them or you haven't...-playing with numbers is not really basis for opinion. If you don't find them as effective in combat then that is the discussion.

[Pavane]

I have tried them in combat. I don't see any appreciable difference, so the additional cost sours them for me.

P.S.
I've started a new game, so I no longer have Blade engines. When I do, I will try an experiment. I will create two Spinal BR designs as similar as possible (with unique weaponry not used on other ship types): one Antimatter BR design and one Antimatter Blade design. My fleet will have two BR Carriers, one with each design. I will fight the same battle twice, but only launch one BR design in each battle. I can then note from the after-combat screen how much damage was inflicted by each design and how many survived.

[Mecron]

or you can have an opinion and be happy with that

[Rossinna-Sama]

I have tried them in combat. I don't see any appreciable difference, so the additional cost sours them for me.

P.S.
I've started a new game, so I no longer have Blade engines. When I do, I will try an experiment. I will create two Spinal BR designs as similar as possible (with unique weaponry not used on other ship types): one Antimatter BR design and one Antimatter Blade design. My fleet will have two BR Carriers, one with each design. I will fight the same battle twice, but only launch one BR design in each battle. I can then note from the after-combat screen how much damage was inflicted by each design and how many survived.

I think this here is why the engine type doesn't seem to be doing it for you. As you mentioned before, the main advantage the blade\streak BR engine has is its improved speed and time on station but its weaker in a direct fight.
Wouldn't speed and time on station improve longer range BR options more? Try placing them on a Torpedo BR armed with one of the tracking torps such as Enveloping Antimatter. Due to how the AI works with them, they will fire their torpedo then flee any return fire, and having more speed means they'll be safer from said return fire due to putting more distance between them.