Honestly, there really isnt a trade off with markets betting vs sportsbook. Odds are also far better - e.g. I got Tyrell Hatton @ 25s this week where industry best price was 20. Bookies run a 7-11% margin on their sports books. Smarkets run at 0% (as its trading) but you pay 2% commission. There's free calculators over the internet to show you how much to lay, and you can amend up or down depending on how confident you are of the back or lay winning. And whatever happened you'd have been guaranteed a win as you're betting against an event happening - in your case Louis Oost couldve held his 2nd on the 18th and you're in a world of pain!