I don't think that will be an issue at all.
If there is less ethanol in the mix, it will simply be a greater quantity of petrol. So if you account for 85% ethanol, having less than that won't hurt... it will just mean a *slightly* lower octane.

I'm looking forward to having some cash again so i can get my ethanol fix... It's addictive! (for the car i mean... not for me) 

um but a slightly lower octane, wont that mean the fuel is less knock preventative? So have your tune with x timing might knock at y rpm/load when it usually wouldnt? etc.

I dont think it would be a major issue. If your running a minimum, say 10% on a stock ECU to get to around the 100RON level, and the bio-flex drops off a few percent, it would simply mean the ECU would be back to trimming the JDM ign timing. Anything greater than 10% would put you over 100RON by a reasonable margin, so there shouldn't be enough variation to cause any issue.
With a tuned ECU, I doubt you'd want to run as low as 10% given the performance gains available..there's a real tendency to get greedy with this stuff where thats concerned. With higher mixes  AFR's become the key indicator for safe tuning, as knock just doesn't take place on a healthy engine. Personally, I'd stay away from GM sensors for that reason, and stick with the OEM, and tune conservatively.
If your concerned about the possible effects of the E on the stock pump or hoses etc., I'd look at 15-20% in that case, which from all reports seems to have low impact.

James - Probably was posted elsewhere, but do you know where to get this stuff around our area? I asked the local BP that I go to near Dennis Rd adjacent to the M1, they haven't heard anything about it and don't know where they sell it. I'd imagine this particular servo would have a huge following if it started selling the stuff given the amount of imports around Springwood area.

Do you mean E85?
It's also called E-flex and is a joint project between Caltex and Holden.
It seems to be popping up at a few other places lately.

E-flex is in the following areas. (link to caltex locator is below)
ACT
Nicholls
Tuggeranong

QLD
Mackenzie
Churchill
Marsden
Brookwater
Alexandra Hills
Worongary 

NSW
Casula
Drummoyne
Gosford West
Hamilton
Heathcote
Manly
Moorebank
Richmond
Tempe

SA
Salisbury Park
St Marys
Woodcroft

VIC
Footscray
Hillside
Kilsyth
Lilydale
Mornington
Mount Waverley
Preston
Springvale
Tullamarine
Yarra Glen 

http://www.caltex.com.au/...ndAServiceStation.aspx 
 

The one I've been going to is Caltex Marsden. Its on the cnr of Browns Plains road and 3rd Avenue. The pump is at the back, on its own and I think it was something like $1.14 a Lt.
I'm not sure too many have caught on yet, seemed pretty quiet when I've been there. At Springwood, you'd be knee deep in ricers

It's been publicised for the new Commodores anyway. I would imagine the whooping great warning lever over the E85 pump is enough to scare some people off.
I have heard of a few people filling up purely with E85 "because it's cheaper" and then needing to be towed away. This was from the caltex operator at Woodcroft. 

LOL. I might pop around to that one at marsden. I've always hated going to Caltex for fuel...it's like Aldi to me...and I vowed to never step foot in an Aldi store. Don't ask my why I just made up my mind that way even though I don't mind the produce. I'm a bit hesitant though running it in my car the way it is. 14-16psi on a stock fuel system runs lean enough - will running say 10-15% E85 be more likely to do damage? I need to invest in a cheapy MBC and keep boost down.

^ if you blow it up, then at least you'll have an excuse to buy an S2K... lol
So how are you controlling boost now?? 
 
I really hope that their "proposed" sites open up soon! (North Adelaide :D)
might shoot off another email to the Biofuels manager.

Hard to figure the Aldi thing, I've never been in one, no idea why, maybe something about the name??
10% won't cause any issues, might even solve some. Only thing is going higher might raise the boost a tad, so if your still on the stock HG that could be a worry. Grab one of these..http://www.ebay.com.au/itm/Turbotech-manual-turbo-boost-controller-ORIGINAL-/220630394267?pt=AU_Car_Parts_Accessories&hash=item335e98a59b
cheap and they work well.
I'd go with 6-7Lts on a fill-up and see what you get until you get the boost under control.
Those guys over there are used to me turning up with a 20Lt container..I think they have the idea I'm distilling the stuff -:)