I would whole heartedly recommend! Don't be a sucker trying to shift around your big bag onto the shinkansen/other local trains.. I've done it and it's not fun :D Last time I went it was for 3 weeks and extensively used, IIRC every time the bags were waiting our rooms for us. Excellent service and like the above says, just organise with your hotel (if they don't then I think most conbinis allow it?).

any particular companies you would recommend? I tried Luggage Free but their website doesn't seem to be functioning (never gives me a price estimate - tells me to call the office. When I call the office they're always not at business hours)

Your hotel is already contracted with one of the forwarding services. They will arrange it for you.

If you're staying in a hotel, they'll take care of it for you. If you are not staying in a hotel, there are 2 leading companies, Takkyubin and Sagawa:

https://www.kuronekoyamato.co.jp/ytc/en/send/services/takkyubin/

https://www.sagawa-exp.co.jp/english/

That Luggage Free is not a Japanese company. Here is one of the most well known, though there are several in Japan.

https://www.global-yamato.com/en/hands-free-travel/scene02.html

Again, your hotel will have a relationship with one. Use the hotel front desk and they'll take care of all of the paperwork. There are also services at the airport. The prices for all are basically the same.

I'm trying to arrange for landing at Narita and transfering my luggage to the hotel so I'm starting at Narita. Do they service all hotels?

Yes, they service all hotels. Bring the name and address with you.

I think they also want the hotels telephone number. Not a bad idea to let the hotel know before hand but not required. For an idea of cost a 160 size up to 30 Kg was 2300 Yen from Sapporo to Yamagata. From Yamagata to Narita hotel was 1900 Yen. Both times I could have carried them in the airplane or the train but for the cost it was the way to go for me.

Cunard line uses luggage forward