Laying: Liability vs fixed stake

It's sometimes difficult to decide whether to lay to a fixed stake or fixed liability. As some of you know, I lay horses in the place markets and it's been pretty successful thus far. 

I've been proofing some selections to Racing Index for Wayne Bailey Racing (they are place lays) and there's a big anomaly in the results. I always layed the selections to a fix stake as the historical results were good:

Racing Index is a site which monitors tipsters and how well they perform. I've been proofing the place lays there since the Summer. The results to a £10 fixed stake though show a ziz-zagging chart since:

But if you have a look at the fixed liability results, the chart is much more steady.  (note that the results for the below are to a £1 stake rather than a £10 stake but you get the picture):

I don't happen to have the full results down through the years to a fixed stake and it would be very difficult to compile as there's thousands of bets. But now I've to decide which way to go. Do I continue with the fixed liability which has proven profitable down the years - or do I switch to fixed liability, which has proven more profitable (and consistent) lately?  Long term steady success - or short term profits?  Both are tempting.

I might split my bank and do both but it just goes to show how big a difference staking can make on the same selections. 

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Anyway, I was pleasantly surprised to see today's racing go ahead with the weather. I'm going to do a few bets as outlined in today's Irish Independent. Have a good one: