With my DMK 31AF03, solar disc will be around 680x680 pixels when used with my Borg 45ED II at prime focus, it's pretty good and simple to do without using mosaic.
With a 350D, I have just substituted the pixel size into the same formula and the solar disc will become around 480x480, not bad too. With a 2x barlows, the solar disc will become 960x960 which is still well within the large chip.
It's definitely a good ooportunity with the PST-BF5 in straught through configuration.
Let's see if it's a good setup for daily snapshot, I believe focusing will be the main issue. At 325mm, I hope a tripod won't be required, but of course when a 2x is used, it becomes impossible.