In my first test today (training triathlon competition) I used multisport mode and it worked pretty fine. Anyway, as we know, HRM is not working while swimming and GPS is not reliable enough to measure distance.
To get bit more reliable of GPS there was used lower frequency, 15sec, for data recording (by longjog if I remember correctly) and it gives better result.
In multisport mode it would be useful to set different recording frequency for each sport separately because 15sec for for swimming would be good but for bike it is not good at all. What you think?