Binaltechs are 1:24 whereas Alternity are 1:32, so they're not to scale with each other as far as the vehicles are concerned. As far as the robots are concerned... that's subjective and depending on what you would consider to be "in scale." Being 1:32 the Alternities are all smaller than the 1:24 Binaltechs and Alternators, so Alternity Bumblebee does stand shorter than Prowl in robot mode if that's what you're after. But conversely the Suzuki Swift mode will be out of scale to Meister's Mazda RX8 mode too.
Anyway, here's a photo of my Alternity Bumblebee next to BT Skids and Prowl for comparison if it helps. :)
http://i6.photobucket.com/albums/y22...on2011_43a.jpg
P.S.: Acquisition for today... walked into work this morning and found a TFPrime Happy Meal Megatron on my desk. :D