Dual M.2 SSD usb-3.1 enclosure

This looks like it would be plenty fast enough to run a operating system from it. Has anyone used something like this? Can it be used as a boot device?

Linux? Sure. Windows? Worth enough trouble you'd might as well stick with Linux.

Yeah linux will work fine, just make sure the system you're booting from can boot from USB (most modern systems). also make sure to install your bootloader to the USB device, not your local HDD, or disconnect all other storage mediums so as not to accidentally cross install things.
Windows will certainly install on this as well, unless you use a UEFI OS like 8/8.1/10, W7 in BIOS mode will boot from any system assuming USB boot in an option on the machine.

on old laptop I have linux mint cinnamon installed to a MicroSDXC UHS-I card, which can get to 128GB (I use 64GB), and ~100MB/s in speed depending on budget (Mine is 90MB/s), I like my old laptop because I can boot from anything, I find all the new laptops are crappy for boot options, so locked down these days... UEFI sucks.. disable secureboot on new machines, change CSM settings, than only boot from CD on most of them, which means no sneaky booting from USB devices like this lovely old BIOS laptop. booting from the (usb device) SD card slot is nice. no HDD needed, a simple pop out SD adapter card to MicroSD, encryption before bootloader on the card, encryption of OS, encryption on Home partition, whole MicroSD zeroed. ah lovely.

even a single M.2 USB 3/3.1 enclosure is fast enough for a boot drive.

USB3 is 5Gbps - overhead

USB3.1 is 10Gbps - overhead

M.2 Drive Throughput: PCI-E 2.0 x2
Theoretical Maximum Throughput: 8 Gb/s (1 GB/s)
Est. Real-World Maximum Throughput: 6.4 Gb/s (800 MB/s)

a single PCI-E 2.0 x2 M.2 drive will fully saturate a USB3/3.1 port.

Try find a quality single M.2 usb/PCI-E bridge instead of a dual one (unless you need the extra storage space). you'll barely find a difference in performance as a single drive maxes out a USB3.1 port, unless the single M.2 SSD's write speed is to low, a second one in RAID will certainly saturate the USB.
It's like overfilling a cup with water though, once the cup is full there's no more real gain.

Good luck with your venture. I wish to find a high quality super slim M.2 USB3.1 bridge soon too, super useful for large file transfers, client PC backups, etc.

Thanks for that info.

I'm going to keep looking as see what I can find. I've not seen many M.2 enclosures here in the UK at least. So I might just opt for a ssd in an enclosure.

One of the reasons I'm thinking about this is that at the moment I've just got a windows laptop. I'm pressed for time, so I can't spend time moving things around to setup a dual boot. I'm hoping a usb3 enclosure whould be a quick fix/hack for the next few months.

There's a major limitation on that SSD enclosure though.. only Sata type B key M.2 SSD's...
Also the ebay seller is just reselling it straight off of AliExpress

Thanks for the warning, I didn't know what type B was till now.

I was just posting that as an example while I was browsing for sellers in the UK.
Not bought anything yet as not found something like that here yet.

What I did end up getting though, for part of my backup strategy:

It was cheap and it has a switch built into it. So at the end of the day, I flip the switch, pc detects the drive and does it's daily backup then suspends.