If you're a retail investor trying to "trade" stock CFDs, then...

If you're a retail investor trying to "trade" stock CFDs, then trade a DMA model, you should not see any difference between that and the underline. I'm not sure why you would trade a MM model.

If you're placing limit orders, then you can't always expect them to get filled. It doesn't matter if you're trading the underline product or a synthetic CFD. If the liquidity isn't there, or someone else is ahead of you in the que, then you're often not going to get filled. Less liquid markets like the ASX play into the hands of market makers , since they often force you to cross the spread in order to get filled( eg buying the offer/ selling the bid), which is traditionally how MM's make money( They're buying the bid and selling the offer).

The biggest problem with CFD's is that retail investors don't understand what they're doing, they lack the domain skill. Most are used to "investing" in stocks, they then start trying to "trade" stocks on a shorter duration with greater size. Most end up getting burnt.

Also, "trading" ASX equities can become more challenging since commissions are priced on a per $ basis, instead of a per share basis( Like US equities). For example buying 100k worth of BHP is typically going to cost you 0.1% per side( so around $100), however buying $100k worth of apple( eg 757 units @ $132) will cost as little as 0.005 per share( so around $3.80- via the likes IB). The higher exchange fees from the ASX can severely impair a retail traders profitability( You need a greater edge), this restricts you from day trading any "blue chips"( so you have to carry more overnight risk, or gamble on penny stocks), making money management more difficult. You can get around this by restricting your size, and extending out the duration of your trade( which is probably advisable anyway), however it's still limiting your opportunities and hurting your bottom line when it comes to trading.