I used 3U Armortec 900 Technique as my main for many years and recently purchased 3U 88s a couple of months ago (still trying to transition to this but undecided if I actually prefer it).
My experience with the 88s is not extensive but in my opinion they feel very different. Even when dry swinging the rackets the 88s is definitely more head heavy and the swing requires extra force. AT900 is still head heavy but the balance is a bit more even, therefore easier to swing. The new astrox material feels nicer and more modern compared to the much older armortec, whether it makes a difference I can't really say. Rotational generator system of the 88s creates a weird feeling where the racket tries to pull back after you hit the shuttle. It doesn't occur on every stroke, but when it does happen you'll notice it. 88s is also slightly shorter in length which may take getting used to.
Both rackets feel great when playing net drops and drives. For head heavy rackets, they are quite easy to manoeuvre. I am not a heavy hitter so smash power wise I felt they were similar.
My advice is to find someone who has the racket and try for yourself. I am sure you will notice the difference instantly.
