My friends and I have "standardised" on MESH2. We have a mix of SENA and Interphone. They work seamlessly together with no lock-in (unlike proprietary Cardo, which only works easily with...other Cardo).
I have Interphone UCOM 16. Last time I looked Sportsbikeshop were selling at £149...bargain! Just checked, now £159
https://www.sportsbikeshop.co.uk/motorcycle_parts/content_prod/537620
Had mine 2 years and 3 Euro trips so far. Battery life on my own (i.e. with MESH2 switched off, just listening to my NAV6 via Bluetooth) is fab (2 days!). With MESH2 on constantly, and listening to music, about 8 hours riding time between charging.
The comms is great for "look out!" moments (watch that pothole, watch that sleeping driver), as well as planning petrol, coffee and pee stops etc. After a while the chatter subsides a bit but they are really useful. Range is good with MESH2 as well, so if the guy at the back gets separated a bit, they can still either (1) let you know so you can wait, or (2) the leaders can give directions...
If anyone in your squad has an older bluetooth-only SENA, you can get a MESH adapter to make it compliant... Here:
https://www.sena.com/us-en/product/plus-mesh
With either SENA or Interphone units, you just press the MESH button once and that's it! It pairs up with any other MESH2 units in range. It's that easy! The Mesh button is situated so you can easily press on and off whilst on the move, with a gloved hand.
You can also have a private mesh if you want, but we've never bothered.
Once or twice (like getting a ferry with 200 other bikers) we end up getting other riders in our MESH group! As we only ever bother using channel 1. It's a bit of a laugh when that happens. You and your group can use another channel (there are 8 IIRC) if you want privacy, but TBH it's not an issue.
We've been extensively in Spain (as well as Portugal and loads of other countries) , and even stopped by the police, who only wanted to make sure we had UK stickers and legal exhausts (and sober!)