Lenovo SIF: Agreed, it's required for their other software.
Yoga Mode Control - Not actually necessary from my experience. I have the service stopped because it uses 3 - 5% of one core at all times. When I fold the laptop into tent, tablet, or keyboard-facing-down (stand?) mode, the keyboard and touchpad still get disabled (sometimes takes 3 or 5 seconds). I don't ever want Windows 10 Tablet-mode becuase of how it hides the desktop, but I think it would still enter Tablet Mode if I wanted. Also, auto-rotation still fully works. I've had YMC disabled for over a week and I use all 4 "yoga poses". The only thing that YMC being disabled seems to do is: the onscreen keyboard won't pop up automatically when you enter a text-input field. I don't mind since it's easy enough to touch the keyboard icon in the notification area. Oh also, I think with YMC enabled, you get a little on-screen text when you change modes. These two missing features are not important to me, so I prefer to save the battery life used by the constant draw of of the YMC service and keep it set to manual (I've checked and it never starts itself).
Lenovo Utility: I think some of the options in Lenovo Settings are missing if you don't have Utility installed. Not sure about this, but at one point, Lenovo Settings was missing options for touchpad, camera, battery gauge, etc., and I know that I had the SIF installed. Pretty sure I didn't have Utility installed.
Lenovo Companion: I actually kind of like this app. It has a little hint of bloatware, in that Lenovo kind of advertises new software. But it is a useful app, especially when first setting up Windows, because it downloads the latest drivers and patches. It doesn't force bloatware onto you at all. The layout is pretty slick, too. If you just install Windows 10, then get Lenovo apps on it, then use Companion to install missing drivers, you'll be pretty much set.
Overall, I wouldn't call this Lenovo suite of 4 apps "bloatware". Definitely not as bad as the HP's I've had in the past, and Dell's for that matter. I also don't really care about bloatware since the first thing I do with a new laptop is wipe it and install a different OS. However, I still have the Win10 Home partition that came with this Yoga 720, and a separate partition with Win10 Enterprise. Dual-booting, one for work, one for play. Quite telling of my priorities is the fact that the Enterprise/work partition gets 100GB while Home/play gets the other 850GB.:smileyvery-happy: