are they worth the hype/expense?

i have a set in my garage, that i never used, bought second hand, 2 of which have 4mm ish tread the other 2 are well under the legal limit, they are the medium hard compound.

now ive been meaning to do a few track days in my focus but because of work/family comitments i havent done any, would them being stored in a garage affect them (lowest temp maybe 4-5 degrees?)

im thinking of buying another pair and using them soon, but concerened each pair costs circa £500 and if i buy 2 new ones, are the old ones gonna be useless, i have heard stories of track tyres going off and being sold on and the only way to know is to drive on them? i dont wanna book a £200 track day, take a day off work, fill the car with fuel and find the tyres let me down, but i also dont want to spend £1000 on a set of tyres!

have heard the federals are better value, and there are also R888's (about £200 cheaper a set of 4) but i take all advice with a pinch of salt, quite often people buy cheaper tyres and say they are just as good as they have saved the money and tolerate problems (see falken )

any words of wisdom?