This is true from a pure DSP perspective that Helix is more powerful. From a "number of fx" perspective it is often less capable than HD500X and about on par with HD500. Throw two Plexi models on a patch and you've already consumed one entire DSP. You can then use the other to add a few effects blocks. In fact, with two Plexis and one Tile reverb there isn't even enough DSP power left on that path to add a simple Gain block.
The "pinto vs. ferrari" comparison is much less accurate than "pinto vs. mac truck" since the mac definitely has a bigger, more powerful engine, but that doesn't mean it accelerates or corners faster. Each is made to do its own thing and appeal to a different market segment. Some will like one better than the other. Neither is a clear winner in all situations.