You could definitely go either way. I'd be in the same predicament if I bought one. As your intention is to use it for larger waves the 5'10 is a good shout. But if you like the feel of a shorter board the 5'8 would work for you too.

nev at 70kg and me at 90kg and both your height ride the 510 with futures sa3's.... THE most rewarding, free, fast, loose, drivey, bitey, forgiving board ever...handles ANY wave you dare paddle it onto...you could also ride the 508 as phill said... but if you can stick the boot in, then its hard to walk away from the 510... i say all this as someone who ONLY likes chippy conventional pro boards...(now taking a journey down the tomo path too).. nev talked me into the hellfire when it was first born and i grudgingly agreed to try it.... the rest is history... the forum have had to read page after page of hellfire FROTH....!!!..could happily ride this board everyday...even on the reefs...

note... i cant get anywhere near the magic with any other fins.... these meld perfectly with the board....

I've been waiting for Core's Hellfire FROTHING response since the tread was posted. I think Core's enthusiasm for this board still make me want to try a 5'10" despite my dislike of my former 6'0" Hellfire.
What size Vanguard are you going for Core?

I think I'm going to order a 510 Hellfire in Kiting construction for me and the old man when the wind is up. I'll have to try surfing it though based on Dave's borderline lunatic raving on it :D

Yeah, I seriously feel like I'm missing out on something everytime he posts on the HF, even though I didn't particularly like the one I had. I am convinced that the 6'0" (for me) (and clearly for Dave) has too much volume. I am always on the lookout for a 5'10" demo or 2nd hander to try out. Not that I need another board anymore!

i rarely get down to scum valley these days...come up and try it sarge... cant speak for fst which is heavier and different flex... the light and sparky rapidfire adds to the hyper responsive nothing under your feet feel...as do the sa3 fins which are in balance with it...

506 vanguard was the call... since i hate straight/full outlines on hi-perf short boards, it will be interesting to try and feel out what makes this design perform outside the previously understood parameters... major departure from what we all knew..... exciting times...just wish i wasn't getting too old, slow and broken down to push these new designs..... oh to be a grommet now.... mind you, the old loggers thought the same when we were playing with the early shortboards..... circle of life..!!

Thanks for the offer, but it is so hard to leave the perfect unspoilt oasis of the Bondi.
On the other hand- I have been trying to get up to the CC for about the last 3 months, but swell, winds, and work haven't combined to see me head that way. If I do manage it, I will be sure to have my 6'0" MB in the car in case you would like to try it out. Only 1 more more month for me until I am off to Vicco for autumn, so I will have fingers crossed for some good swell and winds soon.