I have sampled some of the local Nigerian sites and this is what I have observed. At small trades, a few of them are fine in terms of speed, however, at peak times, one may have to wait longer than the so advertised moments before a deposit or a withdrawal can be finalised. There is also a different level of reliability of the same platform, as an instance of one platform going offline in the month leaves the user in distress, whereas another platform was efficient and clientel pivotal.

The point is that it is such a fine idea to help local exchanges, yet it is better to start with the small amounts and observe how they work on it and what results are to be expected by withdrawals, customer service, and expenses. Meticulous trading I still prefer to use the larger international exchanges to be safe, though in general simple, and in the meantime daily trading or other methods of introducing new persons to crypto, a few of the Nigerian exchanges are gradually gaining some traction.
The actual implication of this is that local does not necessarily mean better but it can be experimented and the experiences exchanged to be learned by the community.