At present, any MP absent from the House for whatever reason, and unable to return when a vote is called, simply cannot vote. That means that:
Under the electronic voting system which is an essential part of PFPTP ProFirst, it would be possible - and indeed desirable - to allow MPs to vote wherever they are. Their vote would be securely verified.
A further advantage would be that the actual votes cast would be recorded against the MPs' names so that the electorate would be able to see which way MPs voted on particular issues.
There is also the - perhaps rather longer-term - possibility that the members of the regional parliaments within the UK could function also as their region's representatives in the UK parliament for those matters - and only those matters - which affect the UK as a whole (defence, foreign policy, finance, etc), while dealing with those matters devolved to their region solely in their own parliament.
This would mean that Westminster would - as noted below - return to being the English Parliament for all matters which concern England alone. And that could be achieved by UK matters being dealt with on specific days only, and/or by the use of remote conferencing and voting systems linking the four regional parliaments.
Before modern communications systems (both transport-based and electronic) became available, it was necessary to gather all those who need to decide on matters of state in a single location: this no longer applies. To do so is needlessly expensive, particularly when duplicate members of parliament are needed for regional and national parliaments, but representing the same voters.
There is of course the added problem which has become increasingly apparent since the devolution of the other regional parliaments, namely that England has had no parliament of its own since the Act of Union in 1707. Thus, matters such as health, education and transport affecting England alone (they are dealt with separately by the regional parliaments for their own areas) are voted upon at Westminster by members representing constituencies in the regions outside England entirely unaffected by the result and who therefore have no mandate to do so.
PFPTP ProFirst, by giving MPs from each region (including England of course) a voting power proportional to the votes cast in that region, would for the first time allow a completely fair allocation of voting power between the regions for those matters concerning the whole UK.