To know if any one Maltipoo puppy would be more prone to a drastic changeover as opposed to a more subtle hair loss, we need to look at the Poodle and the Maltese for the answer, since the Maltipoo puppy is the product of both of these purebred dogs. Elements from both breeds will come into play. Do keep in mind that when it comes to a question of puppy hair loss, it does not matter which breed is the dam (mother) nor which is the sire (father).
Poodles have a clear-cut and noticeable change from puppy coat to adult coat. Therefore, with this breed, puppy hair loss is normal and expected. It happens at just about the 1 year old mark, however with some it may happen as late as 2 years old. Since it is the Toy size that is used in breeding a Maltipoo, the 1 year old time frame will most often apply regarding this issue. Hair will fall out quiet a bit and then a lovely adult coat will set in. Most owners will find that a soft curled coat will be replaced by a more tightly packed curl coat... a more soft wiry coat by a moderate wiry coat and so forth... coat type does not often change with this breed.
With Poodles, it is typical for there to be a color change; adults hairs will grow in with a different color than the puppy hairs that they replace. While one cannot go from black to white, there can be a lightening (fading) or a deepening of tones. A touch of a secondary color may come in strong or it may clear out, leaving the main coat to be closer to a solid.
Maltese are a bit different...They have a slow change over from puppy coat to adult coat that is not as noticeable... many owners do not notice it at all. It generally begins between the ages of 10 to 14 months old. It is not severe in most cases...hairs will slowly fall out to be replaced by adult hairs.
Therefore, if a Maltipoo has more Poodle in her than Maltese, it is highly possible that the puppy hair loss that is experienced will be very noticeable and with color change as well.