Originally Posted by Road Fan

As far as making a comfy bike out of it, I think the Merkcx is ahead. The frame geometry used by EM usually has the seat tube angled less upright than other road bikes by a few degrees. This could make the bike more amenable to a higher handlebar.

SLX is made of Columbus' version of CrMo, called Cyclex. Essentially nothing sets that alloy apart from the CrMo of today. What sets it aside from Columbus other archetypal tubing SL (also just CrMo) is that SLX has helical ridges inside the butted area of the main tubes. This adds a little strength at the ends of the tubes and adds a little weight compared to SL, and some folks think they can feel a little added harshness. I couldn't say, and the Magnificent 7 write-up was not conclusive. I have a frame which I like a lot and I believe to be SL, but I've never owned or ridden an SLX frame.

The Niobium is made from a much more modern and stronger steel which Columbus calls Nivachrom. It's specs show it is about 150% stronger than CrMo based on metallurgical lab tests. To make a Nivachrom frame that is as strong as a CrMo frame, you need about 33% less Nivachrom all else being equal. The Merkcx should therefore be lighter, more lively, and perhaps better at shock absorption than the Massi frame. Again the Merkcx favors your goal for comfort.

I would not buy either at the moment, but that's mainly because Mrs. Road Fan has begun to steal my bikes and parts that she thinks would work better under her butt than under mine. If I brought the Merkcx and the Massi into the house, I'm sure she'd swipe the Merkcx. And I don't think I'd buy the Massi by itself. If it was a Masi, it might be different.