True, your experience is odd. It's a deserved reputation the Grado's have, I was impressed with mine from first listen, but the next best thing I'd heard before that was CX300s canals. Who knows, it could be you have some underrated phones in the technics.
Even so, I heard many other more expensive phones on my Grado buying visit and my first reaction was 'why are these so much?' They didn't sound that much better from the Grado's.
There isn't a massive blow away factor with phones in my experience - the differences do take time and ear adjustment. I've bought some 'better' ones since, and they don't knock my socks off, they just do things differently, and some things better than the Grado.
In fact, the thing that has lifted both my phones considerably is adding a really good source, such as the DACmagic, and even that took a few hours listening and some differing music, to adjust to it and realise what they were doing - then I really was impressed.
See how you go, they might blow you away yet.