I own a tanning salon where we own all our Sunbeds but we have Flabelos machines on profit share,
I personally would go for the rental first to see how you got on as its only a 3month contract.
The plus side of profit share is that they usually either pay for retubes or at least contribute towards them.
Both options would be likely to include maintenance.
The way you need to see it is if you went for the rental at £46 per week & you offered minutes at £1 for 3mins, you'd need to get 138 minutes worth on your Sunbeds per week. I'd divide that by the amount of days you are open eg if you open 5 days.. 138 / 5 = 27.6! If you feel you can get more than that a day, then rental should be fine.
If you went for profit share, you are tied into the contract for longer and will automatically lose 50% of your takings! At least with rental, you only have to cover minimal rent.
The sunbed will be quiet to start off with as this can be a quiet time of year (apart from christmas & New Year rush) but at least word of mouth will get round before Summer.
Good luck
if there's anything I can help with, feel free to ask & I'll try my best!