Do I think we're in a simulation? No. But though the reasons why a perfect simulation is possible aren't necessarily obvious, but they are compelling.
Quantum mechanical computation depends on the energy splitting (energy difference) between different levels - different energy levels of a quantum mechanical system oscillate relative to each other, and bigger energy splittings mean faster relative oscillations, which means you can get more computation done. So if you want to simulate a quantum system perfectly in faster than real time, you just have to make a model that is higher energy. The cool thing is that the model doesn't necessarily have to be arranged like the actual system: quantum computers designed to simulate chemical reactions can be just a line or grid of atoms linked by light - as long as the interactions between the atoms are proportional to the interactions in the modeled system, the computer works fine. This would allow, for example, a spatially 3d universe to by simulated within a 5d universe just by making the right connections.
Actually, now that I think about it, that may not be the heart of your post - it may be speculation about "subjective experience" rather than the practicality of simulations, which would make it even worse than I'd first thought.
Yes, you could in principle create a dissimilar but isomorphic quantum system to simulate reality. My argument is that the real one will take less stuff to build by a very large factor, where the factor is large enough that "stuff" can be validly taken to mean any of matter, energy, or negentropy.
I've written a prior post about how I think that the Everett branching factor of reality dominates that of any plausible simulation, whether the latter is run on a Von Neumann machine, on a quantum machine, or on some hybrid; and thus the probability and utility weight that should be assigned to simulations in general is negligible. I also argued that the fact that we live in an apparently quantum-branching world could be construed as weak anthropic evidence for this idea. My prior post was down-modded into oblivion for reasons that are not relevant here (style, etc.) If I were to replace this text you're reading with a version of that idea which was more fully-argued, but still stylistically-neutral (unlike my prior post), would people be interested?