Cheers for the response Manticle.
The IBU's were one thing I was tossing around a bit, and will probably do as you suggested. Should I leave the OG's the same for both?
I'd normally be getting onto some liquid yeast (and still very well may do that) as the S04 is a little sub-par, but as it's more just to use it up, I was probably going to stick with it.
As for the hopping, i was going to go with a mainly cube hopped ESB as I've never used styrians before and only hear good things about them so was going to do that to get a pretty good idea of the flavour and aroma of them.
With the porter it'll probably be mostly an FWH addition, with a little thrown into the cube.
Heritage crystal would definitely have been used as I'm getting a quarter sack of it in a BB but ive only got the med and cara on hand atm.
Might even leave the midnight wheat out, it was more to help the roasty flavour along without the bitterness of roast barley as I've got a bit of that on hand as well. Might just up the spec 1 instead...
Cheers heaps,
Sponge
Gravities are fine if you were to swap the IBUs around. I make my bitters between 1040 and 1055 and between 35 and 50 IBU. Porter is between 1050 and 1065 and usually 30-35 IBU with no real need for late hopping (don't pick much of it up). For styrians, I'd still look at at least a 10 minute addition (and I'm talking no chill, with no adjustment - just 10 mins as 10 mins) but they work anywhere - bittering, flavour, aroma and even dry.
A lot of people say roast barley and black malt have no place in a porter but I think that's bollocks.
It's about balancing the ingredients and not using with a heavy hand. I use both black and rb in my porters. I hate quoting the bjcp at anyone since it's hardly the be all and end all of making good beer but since they seem to have invented a few styles of their own (including robust porter) then even their guidelines suggest some black and roast is OK as long as it's not excessive (then it's a stout).
For me, I think about the flavours I want in the final product.
For esb, that's biscuity, nutty and a slight caramel with a lingering bitterness so I use MO, biscuit or victory and a good crystal. Hop accordingly with nice UK appropriate hops - favourites being challenger, EKG and Styrian.
For Porter that's nuts, chocolate, coffee, toast and biscuity so I use MO, biscuit/victory, chocolate and a teeny bit of crystal, RB and black. It's a long way from getting confused with a stout.
I also cold steep my dark grains overnight and add to the last 10 minutes of the mash so there's no evidence of overly roasty, inappropriate ashy type flavours in the final product.