Can we just get back on track , about the Safari vs the Eco. Personally neither of them really impress me, in fact both disappoint me and thought over the years I had a number of them , they either end up gifted away or wasted in the office pen bin. The TWSBI Eco had their problem regarding the materials that's a given. I've seen fair share of this in play and I find the styling not that much pleasing. The Safari , while styling vise stand better, its the inconsistency as well as the section that made me abandon it. Let's be honest, none of both are bad pens, but so too are pens like Wing Sung 698, or Parker Vector, or Pilot Cavalier or multitude of other pens be that up market or down.
I happen to be able to try the new Eco-T for a while and I must say the triangular styling does not really improve on the basic Eco design and the Blue made it look more like a teen play on the theme than anything. Needless to say I had found the Lamy Dark Lilac, Petrol of more stately color and finish.
But the single most important difference between the Eco and the Safari, obviously is the filling system .. so to put it bluntly its about whether one need / prefer a certain filling mechanism, and the good and bad that came with it. There are other subtle differences, the snap cap vs the screw cap, the Demo barrel vs the solid color. The tough ABS vs the clear PMMA acrylic. The kind of finishing available and then of course the cost of the pen. If I am asked for a choice, I would gravitate towards buying a Lamy with a M or B nib in some of the darker Satin finish like the Charcoal, or Dark Lilac.