our new SDL Trados Version (2017) only supports MIF 2015 Format and not yet MIF2017.
you can go into SDL Trados Studio 2017 into the Options for the MIF filter in your Studio project template. Activate "Process unsupported file versions". Now you can import FM 2017 MIF files.
As there are no changes in the MIF format in FM 2017 (14) compared to FM 2015 MIF Format (13), this should work without any problems (you might want to double check with SDL).
re: our new SDL Trados Version (2017) only supports MIF 2015 Format and not yet MIF2017.
What does "support" mean? If it refuses to process a MIF that has a 2017 header, that's one thing, but if it merely ignores any features new in 2017, it may work anyway (especially if you avoid using 2017 features).
Because MIF is backward and forward compatible, FM historically did not provide the same rev-1 save for MIF that it does for binary .fm (an exception is that it appears that FM8 and later provide save-as-MIF7).
re: Can I save as MIF2015 with a trick?
Possibly: Avoid using 2017 features. Save as MIF (2017), and edit the header line from <MIFFile 14.0> to <MIFFile 13.0>.