I have done it. 6 screws to get the old one out, then lift and carry off (two man job).
New one was the same size so i just plugged it in and stuck it in the hole. my 60+ year old father and i did it on a thursday night in about 5 minutes. 6 more screws to secure it to the cabinet.
Double was not as heavy as i thought it would be. the key is to take the doors off. they should come right off if you open them a little bit and then pull them up (toward the celing)
We just installed a Stainless Steel Kitchenaid double convection oven. It would have been a snap except that the hole in the crappy cabinets that we have ( we're fixing to replace them, the oven was the first step in renovating the kitchen) was too small by about an inch. A trip to Home Depo for a sawsall saw and 10 minutes of cutting and voila! big enough opening! Hooked up the electricity and turned the oven on, peeeeeeeewwww!!!! the first few minutes stank pretty bad as the manufacturing oils burned off but after that
Best thing of all? we got the oven at Sears outlet and got a $3,000 oven for about $1,500.