I honestly dont think anyone needs to go to the expense of £200 - £300 racking but if it gives piece of mind, go for it.
I dont fully agree with the statement that if a lipo catches fire in a good fire retardant bag you wouldnt have much chance moving it. Yes, if you leave them unattended them come back to them when they are alight but if you actively monitor charging lipos, you get an indication something isnt 'right' before they let go. That could be a crackling or popping noise, a smell or signs of smoke.
If you see any of these, dont take any chances, stop the charge quickly and get the pack out of any building, not necessarily in that order!
Im not talking one of those lipos 'sack' things. I have two lipo fire resistant \ retardant bags which are more like stand alone boxes. They have two flaps which cover each other plus a top cover over them which velcro's at the front.
I keep a hefty pair of wire cutters by my charging set up so if the worst happens, there's no mucking about trying to disconnect the charge leads. It's a straight cut through the wires and out the door. No need to bother after short circuits when cutting the wires if the thing is igniting.
Just my way of organising things though. Others have different ways and methods.