I'd go with 8mm bits if Whiteside made them for my uses. They only make 1/4" and 1/2" bits in the styles I use though. As much as I like Festool stuff, I'm not buying their bits. I can get 3 Whiteside bits for the price of one Festool bit (at Holbren.com). I'm sure Festool bits are excellent, but there's no way they are three times better than Whiteside. Whiteside is top notch quality, so its not like I'm comparing Festool bits to something like the bits from MLCS (junk).
Lou, I have not had time to read all of the posts below, but I had the same problem. I have a few 1/4" bits which were gathering dust as they did a lot of slipping in the colletts of my PC router. some slippage even with my Milwaukee. I could find nobody who sld 8mm other than Festool. I have always like the Whiteside bits and called them on phone. they do have several 8mm bits (3 yrs ago when I called) which were identified in catalogue with an *. I promptly ordered a few of my most used bits in 8mm. I also found that those 1/4" bits do NOT slip[ in the Festool OF 1000 collett. So i have a bonus. i did not throw out my 1/4" bits, I have a few 8mm bits and I liked the OF 1000 so much i finally sprung for the OF 1400 which can use all of my bit supply. Any replacement bits will, however, be of 1/2" or 8mm from now on. Even if WS discontinues the 8mm.
Tinker