I couldn't agree more, the new X-Lite makes dialling a pain in the backsite.
I am one of the techs from a UK VoIP company, and have tried supporting some companies using X-Lite 5 but, to be frank, it's a complete nightmare.
First of all, it seems to be completely mandatory to have a dial-out prefix. This prefix is prepended to ALL calls. There's quite a few VoIP providers out there that DON'T have a prefix for outbound calls.
Secondly, X-Lite 5 will attempt to put the international call for your country code before all national calls but, does this without the international prefix.
So, if you're in the UK, have your dial-out prefix as "0" and your international prefix as "00" and dial a UK number, for instance, 01234567890, XLite will dial 0441234567890 (prefix + country of origin + number). A good proportion of carriers will not recognise the fact that the country code is at the start of a number, without the international dial out prefix. However, if you dial a US number, +11234567890 for example, then XLite will dial 00011234567890 (dial-out prefix, then international prefix, then country, then number).
The behaviour is inconsistent and, worse of all, it can't be turned off. It would be much better to have the ability for XLite to send the number exactly as dialled, to the VoIP provider.