Big questions:
which ATEX rating?
ATEX isn't ATEX, there are different ratings available and you'd need the one specific for the job not just any.
(Sorry just noticed a similar question in an earlier post)
Since the level of protection partly depends on the temperature of the surfaces of the device a higher ATEX rating will in most cases get you a low output light.
Modifying lamps between the different uses may look like an option, but it's just to easy to forget certain parts or damage seals. You may just use some of your nice rechargeable batteries instead of the normal ones specified for ATEX.
I'd rather go for two lights, one for professional and for sporting use. Get a proper light for each job.
If it needs to be one for professional and sporting, get a fully sealed one and keep it like this. All in one mining lamps might be an option, but you pay a lot for a pretty low output with a terrible lightpattern and -colour. But they're fully sealed.
If you get one for each job, get a Wolf, UK or Energizer ATEX if they have the right level of protection and you should have enough spare for a good light for sporting use within the budget of an quality ATEX mining light.
Matter of fact, I wouldn't accept any other lights at a mine than the ones provided by the mine if ATEX was a requirement there. Just for the simple reason that the ones from the lamproom have a proven record and should be ok. Lamprooms aren't perfect, true, but it's unlikely that the lamps have been (heavily) modified as mentioned in an earlier post. Even if these were put back to the manufacturer's spec at home I'd still treat them as being tempered with. Even an oldfashioned OLDHAM would need a complete check as it might contain a brighter bulb, automatic fuse or seals might be damaged in some way turning it from an ATEX rated lamp into contraband.