I would not say that conversions made at POSs is that great feature. First of all, a customer is not aware at what rate he is making a transaction, so basically he would need to go somewhere to check the current BTC rate (presumably, to Bit-X or Xapo websites). Therefore, I would not call it convenient and easy to check btc rates every time you are going to make a card transaction.
Mosts users (myself included) check the exchange rate regularly so they already have an idea of the rate at the time of their transaction. If a specific rate must be known, a simple widget on a user's smartphone will do the job.
At E-Coin you need to make a conversion once, being able to choose from 3 fiat currency. It takes literally a second. Afterwards, you can pay with applicable fiat not worrying about rates, fees etc.
Once, but in advance. Most crypto users prefer to deal in terms of BTC rather than fiat. This means they would prefer to hang on to their BTC for as long as possible before initiating a transaction, which you can't do with e-coin. Why use BTC at all, if you just convert all or most of it into fiat for spending over time?
Bitcoin can help people to avoid paying extra fees to banks.
True!
However, with this "true-debit-card-solution" users will be always at risk of being charged due to possible unfair rate or lose money due to market fluctuations.
You just described the issue with e-coin and other prepaid cards (that must be preloaded).
With Bit-X you charge customers for every transaction, even online ones, which is ridiculous.
Fees are straightforward: 0.01 BTC + 3% for ATM transactions | 0.002 BTC + 1% for POS transactions (which is either in-store or online).
And this is really strange that you tell everyone that your technology is built on something else rather than a prepaid one and the same applies to Xapo.
It may be the same cards but the infrastructure built behind it is very different, which enables these real-time conversions.
As I described above, the conversion at POS may have some advantages and disadvantages but it is pretty much the same solution anyway
In the end, it's up to a user to decide what they prefer and what suits them best.
For me (and many other Bitcoin enthusiasts) I want to keep my holdings in BTC/LTC for as long as possible and only spend exactly what's needed only when I swipe the card.