I have the Montane Minimus Pants and my wife has the Montane Minimus jacket. Both use Pertex Shield+.
My durability concerns are with the membrane (as opposed to the face fabrics being used). My rain pants were waterproof initially, but after a few months of regular use (hiking, biking etc) they started leaking heavily (not just DWR failure) and about the same time the membrane starting bubbling off inside the pants. My wife's jacket which has seen far less use is just fine. I think this membrane is fine if you're carrying rain gear that really only gets used a few times per season, but if you use rain gear regularly and/or want it to last many years then I suggest going with something a bit more robust. Generally speaking, a lot of 2.5 layer membranes have bubbling issues after moderate use, but the Pertex Shield+ bubbled a lot quicker than my previous jacket (Marmot Essence).
There are some darn nice 3 layer rain jackets now in the 7-9oz range that are substantially more durable. Haglofs Gram Comp, Arcteryx Tecto FL, Mountain Hardware Blazer, Montane Spektr etc. come to mind. I don't have a problem with the light 15D face fabrics (nylon) being used, but the ultra thin membranes with very little interior protection can wear off pretty quick – especially under pack straps.
Anyways, it's a tradeoff in weight, durability and price. The right choice is an individual call. With that said, my GoLite Reed rain pants weighed the same (4oz) and were in pace to last much longer than my Minimus. I wish I hadn't sold them. Currently I've still got the minimus pants but I painted them with tent floor sealant so they're 0.7oz heavier now, waterproof again and seemingly not breathable at all.