The mood tells me that one "single" lawyer for HashFast won't be enough. Shall we see how many are incoming...
The sad part is all the lawyers are paid for with your money. 
It sucks to say this but realistically the smart thing to do is to rush over there and agree to whatever just to get some sort of money back on the spot. Otherwise you are likely to get nothing or less then nothing since the fees you'll to your lawyers will be coming out of your pocket also. You know the old joke. When a bear is chasing two people you don't need to run faster then the bear just faster then the other guy. Good luck to all.
I would personally view this advice with extreme skepticism.
A hypothetical case like this could presumably be taken on contingency, and/or attorneys fees may be separate from any recovery.
Of course, there's always a chance of a company disappearing into the night or going bankrupt.
But see my sig.
Yes customers don't go quickly and see if you can wrangle even a little bit of your money payable on the spot from a company that is quickly looking like it will simply close up shop but come pay me some fees so that I may sue them for you. Really? What good attorney in their right mind would take a case on contingency that involves a company with no assets and attempt bitcoin recovery - an asset that even if it existed in the company's possession is virtually impossible to lien or to effectively recover by force. Sure one can do it on principle but still I would personally view this advice with extreme skepticism. This is almost like a prisoners dilemma. HF likely is waiting to see how many people will sign that refund form in order to see how much they have to pay out in refunds and if they can continue to stay in business BFL style. Of course if very few people opt for the refund and instead sue then they will likely enter bankruptcy protection since it's pretty clear the claims of people wanting full BTC refunds would outweigh everything. So for investomers it's lose lose. Don't sign the form and you will likely get nothing or sign the form and get some money but you might be in a race with everyone else trying to get at least something from HF as well.
There are plenty of reasons a risky case might be taken on contingency. This is particularly true where, as here, actual costs would presumably be low (no need for experts, no need for lengthy discovery). Biggest cost would be attorney time.
I'm not advising anyone one way or the other, but I'm skeptical of any advice suggesting people forego potential legal rights at the suggestion of a forum poster and without consulting a lawyer.
Anything more specific and I worry about coming too close to ethical lines, so I will refrain and stick with generalities.