I've been wanting to get a second GOOD car seat for my husbands vehicle for a while. When I saw the drop in price, I ran out to the local stores to "test" the SlimFit out. I looked at the SlimFit and the Milestone, both were on sale (Walmart) for the same price and are basically the same seat. My primary car seat is a 2014 Graco 4Ever which I absolutely adore. It has tons of features and both the SlimFit and Milestone are comparable. Ultimately my daughter and I chose the SlimFit because of the two (collapsible) cup holders. The seat is super cushiony! There is a good amount of cushion in the head and butt area, as well as added lumbar support. Feels more cushy than the 4Ever, but ours has been in use for several years. The frame is reinforced with steel like the 4Ever, but I did notice that the "beams" are not as thick or wide as the 4Ever. No doubt this is why the SlimFit is quite a bit lighter. The SlimFit also features the inRight latch system that is a must have. Pretty easy installation, although the inRight latch belt is a bit harder to get as snug as I want. That could be due to the fact it is brand new. The harness automatically adjusts when you raise and lower the headrest. The seat/base is slightly slimmer than the 4Ever. I am currently testing the SlimFit out in my 2014 Mazda CX-5 (middle seat) and I feel like there is slightly more room for passengers vs when I have the 4Ever in the same place.
The only con is that there are only 4 "recline" positions. I wish there were 5. The 4Ever has 2 recline positions just for forward facing (6 total including "booster mode") which is a plus. I feel like it's a little more comfortable with the added recline. All in all, the SlimFit is definitely comparable to the 4Ever. I would definitely recommend if you can purchase for below retail (I $183, $199 after tax). Added a photo for asthetic comparison.