Saracens' decision to pay their women's team this season is "really exciting", says their England back Sarah McKenna.

Sarries will pay their female players for the first time in a move McKenna says shows their "one-club mentality".

But players from other clubs expressed concern that the move could result in "too much difference" between English top-flight teams.

"A club with more money can get all of the best players," said Darlington Mowden Park winger Mackenzie Thomas.

Saracens show their intent

Saracens have beaten Harlequins in both finals since the English top flight was revamped in 2017.

Less than a year after the Rugby Football Union reintroduced full-time contracts for 28 players, Saracens will now issue retainers and pay match fees.

Worcester are the only other top-flight team that will pay match fees next season.

"It's really exciting for the players, coaches and the supporters alike that the club have become aligned in the men's and women's sections," McKenna told BBC Sport.

"It's Saracens as a whole with a one-club mentality now, and in terms of professionalism and the way the game has gone, there has been a change in the mindset."

Richmond flanker Hannah Field believes the move has to be "sustainable".

"If you bring players in because of the money, are you creating a team that want to play for each other or are you creating a team that want to get paid?" she said.

"At Richmond, we are adamant we can be the team that we want to be without paying players. New Zealand's men play for one another, which is more important than playing for money.

"I think if it is managed well enough, and if we can learn from the mistakes the men made when they went professional then it can be a good thing - but it is a slow process and it has to be sustainable."

'You don't want too much difference between sides'

With no promotion to the Premier 15s, or relegation from it, the same 10 clubs have featured in the league since its formation in 2017.

But with Exeter among the clubs bidding to create franchises, teams that finish in the bottom four could be in danger of losing their place in the top division.

Darlington's Thomas said women being paid to play club rugby is "amazing for women's sport", but warned "right now, it may not be sustainable for every club to do that".

"It is expensive and for the league itself you don't want too much difference between sides," she added.

Firwood Waterloo hooker Rachel Thomas agrees, saying there must be "level ground" if clubs want to retain players.

"Whether it is match fees, accommodation or help with university places, there has to be a level ground," she said.

"Especially when you see local girls coming through from the centre of excellence who are outstanding, but they are 17 or 18 and ready to go to university, so instead of staying in the area with us, they are looking at other universities where there are big clubs around who can support them."

'We want this league to be here in 20 years'

Nicky Ponsford, head of women's performance at the RFU, responded "clubs know that the infrastructure has got to be right".

"Our main aim is to ensure Tyrrells Premier 15s is sustainable," she said.

"We've got to make sure commercial revenues are driven up first before we fully professionalise.

"We want this league to be here in 20 years' time."

The Premier 15s season begins the weekend of 21-22 September, with Saracens beginning their title defence at Bristol Bears.