I am not an electronics guy but suspect there is a difference between cheap msw and pricier msw inverters.
A long time ago I was being wooed my the Thou Shalt buy a PSW inverter or the world will end crowd. The old guys rolled their eyes and did not say much.
I put in a Trace 3624 and used it for 10 years with Flat Screen TV, satellite dish, charging cell phone batteries, power tool batterys, computer, printer, house hold refrigerator, microwave, on and on. The only problem I had was the clock on the microwave would go berserk, but the micro wave functioned just fine.
So me personally I would not run out and buy a new inverter. PSW is way cheaper now than it was, so I might buy one at replacement time.