That shouldn't be a practical issue (I don't think it's a reason not to consider the 500).

The 500 appears to be an odd case. Clearly, it's an old unit. I suspect that Garmin isn't making it anymore (but who knows!) but they still have some/many to sell. It sits at a price point much lower than its "replacement", the larger 510. So it makes some sense to still make the 500.

That is, Garmin isn't making it from some conscious intent to have it as an option to its customers (contrary to what Seattle Forest first said). But, due to other circumstances (that is, luck), it is still an option at least until the stock goes away (as Seattle Forest said later). It still being made intentionally to provide options and there still being old stock around are not the same thing.