Not all projects will find a home with Hosted Weblate, though if you are on Transifex now, that argument becomes one of adjusting for minutia of what is is a greater question of an all-encompassing beneficial move.
Move the ones that want to move to Hosted Weblate now, it is a perfect fit for a lot of projects, whereas the two closed source projects of LocalizationLab could help the others, and it, by not tainting their presence on a shared hub.
TL;DRs
Hosted Weblate presents itself as the god-send of Libre software hosting that Pootle did not, and have not managed to set up yet. They too seemed too concerned with scaling into infinity to not to make the move out of safety, and find themselves equally behind the curve.
Concern for all possible angles becomes at some point procrastination, what is possibly a lost cause with Pootle, and wasnāt ready in Weblate then, is available with Weblate now.
The projects that have security concerns for not being on Hosted Weblate, have developers more than capable of setting up their own instance of either Pootle or Weblate.
In an ideal world, all aspects of community and security combine. This could be done by making even lone instances able to federate their pool of translated strings, dictionaries, and mutual visual updates over to Hosted. Logins are to a very large degree solved, since one can use the ones that most of these instantly moveable projects host their development on.
Localization Lab making its own instance strikes me as not opting for the greater community to share in it, but still putting more eggs in the basket security-wise. Developers have reaced agreement, Localization Lab lacks sysadmins, and the both of them want a shared libre platform.
To me it seems only fitting that Hosted Weblate is used, seeing as they also want to carry out changes to the platform, reaping the benefit of having the sysadmin being the same capable person that develops Weblate. The other person i would trust with this now works for Pontoon, and I want to see more response and results out of them before I consider it to be an equal alternative.
AGPL is better for hosted services than GPL, but Pontoon is New BSD, so for me it starts off playing a weaker hand.
The large sum of money going elsewhere, (and we could minutely disagree how grim a place that is), can actually put to good use in building the tools and community libre software translation needs.
Building libre software translation community with the projects it translates is not possible with a non-free, non-working, spying tool in its midst.
Every project can do their part, paying dividends for what translators have put in, and will be able to, by moving now.
The localization lab could add all the projects in its umbrella to the loclab website, by progress, with the supplied widgets.