I just got contacted by Virtuous Flame who informed me that PS Vita update 1.52 is available (which is confirmed on the official site), and as for version 1.51 back in December, this update is compulsory if you want to use some services such as the PSN (which makes sense) or the possibility to copy files to your Vita with the Content Manager (which doesn’t).
Virtuous Flame was therefore able to confirm that his patches to the CMA (openCMA) allow him to keep using the CMA without having to upgrade. He noted that your console’s wifi must also be turned off, otherwise the console will ask you t update as well. If your console asks you to update to 1.52 and you don’t want to, turn its wifi off (plane mode), then reboot the console. also install openCMA on your PC. This won’t give you access to the PSN, but at least you can use the CMA.
I haven’t verified that myself yet. I also don’t know if 1.52 patches Teck4′s exploit and/or my work on HBL.