If you want more reassurance on the Shure QLX-d, I've had 2 receivers now since right after it's release... over 5 yrs (specifically the g band). In those 5 yrs I've been to 12 different states with it... indoors, outdoors, big rooms and small rooms, city areas and rural areas. NOT ONE DROPOUT on either of the 2 that I own. If this is going to be at your venue at all times, and you want to save money, go with the SLXD. Practically speaking they're identical in that case... but if you're gonna be moving them around different locations... qlx-d is the way to go as it offers just a little bit more frequency options.
From shures website:
Both the SLX-D and QLX-D wireless systems offer digital transmission with exceptionally clear audio, low noise, and >120 dB dynamic range, so they sound virtually identical. There are some feature and performance differences which are not significant to the houses of worship, schools, and small theaters that SLX-D is designed for.
- The QLX-D system offers wider tuning bandwidth (64 MHz vs 44 MHz), and can operate more systems in one 6 MHz TV channel (17 vs 10).
- The QLX-D system is available in the UHF, VHF, 900 MHz, and (in some countries) the 1.5 GHz band; the SLX-D system is available in the UHF band only, which provides more than enough options for most users.
- The SLX-D system offers both the SLXD4 single-channel receiver and the SLXD4D dual-channel receiver; the QLXD4 receiver is a single-channel half-rack unit.
- The latency of the QLX-D system is 2.9 msec; SLX-D is 3.2 msec.
- The QLXD4 receiver is compatible with the ULXD6 boundary transmitter and ULXD8 gooseneck transmitter for use in meeting rooms.
- The QLX-D system offers encryption and network control via Ethernet, which the SLX-D system does not.
- QLX-D can be used with Wireless Workbench software and SystemOn software or the ShurePlus Channels app for remote monitoring and control. SLX-D can be used with Wireless Workbench softwar or the ShurePlus Channels app.