Nice. One can never have enough grinders. Although for granite/masonary/fibreglass grinding and cutting I only use the real cheapo grinders as the dust is a killer, The Hitachi and Bosch ones I have are only for metal.
I bought those a couple of weeks ago on that deal, the only problem I find with Hitachi grinders are the leads always get tangled and they always break the outer insulation near the plug(on the 110v versions)
Oh and the other problem I had when I bought those was, my son(Dangerous Dean) thought it would be a good idea to stop the 9" on his shin... nasty cut :-(
Only got one 9" grinder and its Hitachi. Got it for £20 odd from the local b&q a couple of years ago as the box was gubbed, been a good grinder so far. The twin packs been offered for a while, saw it when i priced hitachi grinders after i got mine.
3x 4.5" and 1x 9" is my limit apparently...gf and mates gave me grief when i toyed with getting another 4.5"...and maybe a back-up 9"...hey-ho.
I used a Hitachi one at the spot I used to work at, the boss got it free with a load of disks, apart from the basically solid inflexible girder of a flex it was a good grinder!! Soon got swapped for some nice silicone flex.
Incase anyones interested, it looks like these will be £10 off tomorrow(fri 02/08). If you look under deal of the day, it looks like the twin grinder pack listed.