It's EXACTLY the reason you mentioned (i.e. nothing can go wrong except it not working) that I went with the riser. Mine never worked and I used this:

TrendNET extender: https://www.amazon.com/gp/product/B071Y7FXWW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You'll be safe with the riser if you plug in the power supply into a surge protector. It's no different than having a PCI bus outside the PC. All mining rigs do this with WAY more demanding (and expensive) GPU's so as long as your power supply is good and a surge protector is sitting protecting the power supply, then you should be fine.

You know what's funny is that you're the 2nd person whose said NOT to do this (had another post which described how to do this). I am pretty sure the WiGIG card will fail if there's a spike (or brown outs) in power but you got to have decent hardware when doing this. The links I provided work great and if you do end up doing this, do the right thing and invest in a surge protector as well.

(EDIT: LOL, just edited the post the same time you did and we both use the same cable but for me, even if I disabled/reenabled the WiGIG card in Device Manager, I would never get it to see my headset and have it stuck in "scanning" mode.)

(EDIT 2: Just adding these reference links from the Subreddit. Looks like the PCI-e extension is more common than I thought):

https://www.reddit.com/r/Vive/comments/a4kryw/someone_got_vive_and_vive_pro_wireless_extended/

1.45dB is 30% signal loss (at 6.5ft which is what the TrendNET cable is, you're looking at hit-or-miss connectivity) so extending the PCIe is much better then extending the antenna.

http://www.fab-corp.com/pages.php?pageid=5 <-- Has details on the signal loss per distance.

https://www.reddit.com/r/Vive/comments/up45qu/what_antenna_cable_to_extend_wireless_link_box/

https://www.reddit.com/r/Vive/comments/umr7uv/help_extending_vive_pro_wireless/

https://www.reddit.com/r/Vive/comments/o9ics0/vive_wireless_adapter_wigig_card_with_pcie_riser/

https://www.reddit.com/r/Vive/comments/d155n4/i_successfully_extended_my_vive_wireless_antenna/

https://www.reddit.com/r/Vive/comments/jhlhlr/vive_wireless_pci_extender_anyone_break_20ft/

https://www.reddit.com/r/Vive/comments/knfwub/just_fyi_a_pci_riser_works_the_the_vive_wireless/

https://www.facebook.com/groups/1758166817760568/permalink/2245600585683853/

https://www.reddit.com/r/Vive/comments/9iy0q7/m2_to_pcie_adapter_works_with_the_vive_wireless/ <-- This one is interesting and for people who want to use the m.2 adapter on the motherboard for a way to add a PCI-e slot for the WiGIG adapter. Might be a good option for some laptop users that want to go wireless.

Problems with the extension cables seem to be commonplace:

https://www.reddit.com/r/Vive/comments/9k2ld1/testing_wireless_adapter_antenna_extension/

https://www.reddit.com/r/Vive/comments/8ksh1c/any_word_on_if_the_official_vive_wireless_will_be/