I meant "at best" since you may experience an abnormal increase in SHBG, though this is unlikely. If this is the case it could be worse than without the front-load, however there is no real additional benefit to front-loading as SHBG will rise proportionally, so at best you will get the same gains overall, at worse you will have better initial gains but worse gains later on.
The ester will be processed, or "decay" as you say, at a constant rate by the esterase enzyme. Provided esterase levels remain constant, this rate of processing is influenced by the solution concentration, the steroid ester, the oil used, and the total dose of administered steroid.
If you inject 500mg of enanthate ester it will be processed at a certain rate. 500mg of propionate will be processed at a faster rate, so the 500mg of propionate would become active quicker than 500mg of enanthate would. To make this example easier we'll just say the propionate ester is cleaved twice as fast as the enanthate ester is. If you injected 1000mg of enanthate you would get the same blood concentrations at the Cmax of 500mg propionate.
Obviously the type of ester affects the Cmax and AUC much differently than this, but I think it is sufficient as an example. This principle can still be used to understand the general idea behind plasma concentration and ester type.
I am horrible at explaining stuff with text, so if you need further clarification I can try.