MCP655 is pretty great and gets the job done.
I think jakus has a point on why its one of the best, but most of the time the mcp35x's get punished by user error
I posted this in someone elses thread. It comes to simple ways to decide which pump you want and why, but we can't pretend when you get a mcp35x it just won't start and it will instantly burn out. Before buying we already know the mcp655 cools itself with the water going through it and dumps heat into the loop, and the mcp35x doesn't. So where is all that heat going? This gets followed up by mounting the mcp35x with the rubber like pad material for it on a surface with no airflow, furthermore setting the pump to a higher rate than needed.
A mcp655 is more manageable because even at a higher flow from high speed setting it will only add to the water temp but can't have any issues, right?
The mcp35x had some nasty issues a while back, I'm under the impression they did change the pcb a bit if I did my reading right
The heatsink and fan is just an obvious purchase for a pump that NEEDS!!!! the cooling.
Yeah they have their pro's and con's, but that mcp655 is not going to outperform a mcp35x. I still like the mcp655 was amazing pump, I just didn't like the massive space it took with or without the top