If you can get a new BD 8" on an HEQ5 for $1349, I'd go for it. Since it's new, it would have at least a 1000d-capable Crayford focusser and a finderscope (there's half your guiding system!) and with your electric focusser bolting straight on to the Crayford, you'd be cookin' with gaz with your 1000d! Use the balance of the $2K you save to buy an MPCC and a good LPAS filter. They're both good long term investments too.
Check Peter Tan
http://www.tan14.com/gears.htm for filters, etc.
As Brendan says, a 10" jumps you up a level in cost, collimation and size. If you get a serious case of aperture fever from your 8" joys, you can sell it in an instant later to buy your fancy 10"
Check that the BD 8" is the 1000mm f5, (shorter and faster) and not the dob 1200mm f6. ( I sold my f6 dob and got the BD f5 used from your expert jjjnettie who lives close by, never regretted it.